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[retro] The Original Diy-street Amd64 Overclocking Guide

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THE DEFINITIVE

OCC AMD64 OVERCLOCKING GUIDE

 

 

 

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  • 1a. Confused by HTT? LDT? FSB? A64??? READ THIS!
    There was a big change when a64 cpu's came out.. Its this weird thing called HTT.. In this section we will hopefully educate you in knowing and really understanding what HTT is and its importance when overclocking..
     
     
  • 1b. Overclocking the HTT bus.. Is it worth it ??
    Many people think.. Im an overclocker and im going to overclock every darn part of my rig until it burns down.. Well this is one thing that doesnt really gain much from running faster then stock..
     
     
  • 2. Which BIOS is best for me?
    Alot of people are always asking which bios goes with this ram and cpu.. Is it -2 or the -3 version?.. Read this section to see the one and only correct answer..
     
     
  • 3. A64 Overclocking
    I dont think I really need to explain this section..lol.. Just remember that overclocking doesnt happen overnight.. And even the most experienced overclocker has problems sometimes.. Have patience and read alot..
     
     
  • 4. DFI NF4 BIOS Memory Guide
    This guide was written by johnrr6 with the help of many people he gives credit to in his guide.. It has alot of info about all the extra memory timings that we see in DFI motherboards..
     
     
  • 5. Important Links
    In this section you will find links to important info.. Plently of MUST READ stuff here..

 

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1. Confused by HTT? LDT? FSB? A64??? READ THIS!

 

Some, or a lot, of us are very confused with the new AMD Athlon64 processor, especially in the area of overclocking.

 

Most of us here are very familiar with overclocking what we term a 'normal' cpu, like the Celeron 300A, Intel Pentium4, AMD AthlonXP etc.

 

AMD64 is really a superior cpu that really performs best when it is overclocked to it's max Mhz...but there is this thing called HTT and it seems to be a giant bogeyman for a lot of us.

 

Please, take a read below, and it will hit you like a ton of bricks like it has hit a few of us (and I'm sure a few that are too embarrassed to admit that they really didn't 100% understand until reading this).

 

Basically HTT is your memory controller's communication speed. Look at your motherboard, and you'll see...there's no northbridge! The NB was the memory to cpu communication point on previous motherboards. That is now integrated into the cpu itself with A64's.

 

HTT is the rate at which incoming memory meets cpu instructions...But if it is not running at optimal speed, then you start wondering why some super clock is not showing the good numbers, or isnt stable, or wont even boot !!

 

On socket 754 cpu's the stock HTT speed is 1600 .. Its best to keep this between 1200-1800 when overclocking to maintain stability.. On socket 939 cpu's the stock HTT is 2000.. And its best to keep this at or around 2000 when overclocking.. The HTT bus is in no way saturated, so even underclocking this a little to maintain stability is fine ...

 

Here is a post by RGone explaining how to figure out your HTT speed with a socket 754 cpu..

The default speed of a 3700+ with 1mb L2 cache is 12 x 200 or 2400mhz; real cpu mhz. 12 is the multiplier. 200 is the bus speed AND the speed of the memory when set to 1:1 / 200 in Dram configuration. The HTT bus speed of that 3700+ on the UT250gb if LTD/FSB ratio is set to AUTO is 4 times 200 or 800HTT bus speed times 2 for a DDR rating of 1600 for single channel NF3 boards. If you set the LTD/FSB ratio to X4 the HTT bus speed itself will again be 800x2 or DDR1600 the Default for single channel NF3 chipset boards.

 

Again leaving CPU/FSB Ratio at the default of 12 for your 3700+ and leaving the FSB Bus Frequency at the stock 200 and changing the LTD/FSB Frequency to X3. You will then have a processor running at its default of 2400mhz same as always. The memory will still be running at 200 (DDR400) and NOW the HTT bus speed though will be 3 X 200 = 600 HTT bus speed times 2 for a DDR HTT bus speed of 1200 or 400 under the default HTT bus speed. Now that is how that works.

 

Now that is how the single channel 754 processor works and is in effect how you figure the HTT bus speed which in effect has little to do with an overclock as long as it is not below about 600 or above 900.

 

Now just to show you that figuring out the HTT is the same with socket 754 and 939 im just going to copy RGone's post and replace it with 939 stuff..

The default speed of a 3200+ Venice with 512mb L2 cache is 10 x 200 or 2000mhz; real cpu mhz. 10 is the multiplier. 200 is the bus speed AND the speed of the memory when set to 1:1 / 200 in Dram configuration. The HTT bus speed of that 3200+ on a NF4 if LTD/FSB ratio is set to AUTO is 5 times 200 or 1000HTT bus speed times 2 for a DDR rating of 2000 for Dual channel NF4 boards. If you set the LTD/FSB ratio to x5 the HTT bus speed itself will again be 1000x2 or DDR2000 the Default for Dual channel NF4 chipset boards.

 

Again leaving CPU/FSB Ratio at the default of 10 for your 3200+ and leaving the FSB Bus Frequency at the stock 200 and changing the LTD/FSB Frequency to X3. You will then have a processor running at its default of 2000mhz same as always. The memory will still be running at 200 (DDR400) and NOW the HTT bus speed though will be 3 X 200 = 600 HTT bus speed times 2 for a DDR HTT bus speed of 1200 or 800 under the default HTT bus speed. Now that is how that works.

 

Now that is how the Dual channel 939 processor works and is in effect how you figure the HTT bus speed which in effect has little to do with an overclock as long as it is around 2000.

 

You got it ? (I hope so..lol) The only thing to keep in mind is that the stock HTT for a socket 754 is 1600 and for socket 939 its 2000.. And when overclocking your FSB Bus Frequency you want to lower the LDT multi to keep the HTT within a acceptable range.. (Socket 754=1200-1800 and Socket 939=Around 2000)

 

 

Here is some additional HTT info from AG just incase you are still a little confused. Please note that this was written for socket 754 but everything you read applies to 939 also with the exception of the acceptable HTT range..

You guys are so wound up on trying to get crazy clocks out of these and crazy timings that NF2's would even scream in fear at...When you begin to realize that raw cpu speed is really what is more important than anything on these A64's.

 

They are a superior cpu when it comes to the things you all want them for (mainly gaming). A 2.2Ghz A64 is great, but a 2.6Ghz A64 is HOLY @#@%! great.

 

You cant really saturate the HTT bus on this cpu (you can however have it cranked too high thereby killing efficiency and thereby ability to get data where it needs to go as quick as it would if done in an efficient manner).

 

Some of you live and die by memory bandwidth. You should live more by getting your cpu to max fsb @ 1:1 to really give it the boost it needs (while keeping the HTT pipe in a good range). Better yet, you should live by the same rule that you did on the NF2/P4...

 

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This is why we are happy we have the ability to drop the multiplier on the cpu. Many of you guys might be under the impression that A64 clocking just got a lot more complicated with this new-fangled A64 thingy. And it was pretty confusing for me at first too...But listening to RGone ramble on about head-scratchin stuff for so long it hit me one day...

 

AthlonXP we tried to maximize total cpu speed along with FSB...for max mhz + max memory bandwith.

 

P4 we did the same thing (and was extremely impressed by those 1200Mhz bus speeds!)

 

A64...AMD put some damn new number in there that is real confusing if you trying to let it be complex.

 

The rule was to clock your multiplier up on unlocked cpu's to find a mhz ceiling, then drop the multiplier all the way down and ratchet up your FSB to find your RAM/CPU's max FSB...Then tried to match it up in a most optimal way to get the MOST FSB while getting the MOST Mhz. (this is the part a lot seem to skip the most in-detail testing and fine tuning from this point forward is where you really start finding 'sweet spots' in the setup you are running).

 

A64 is no different. Some of you might laugh but I was terribly confused by all the new numbers (well only really one haha but it seemed like a lot) on the A64...mainly this thing called HTT...and LDT...

 

And really...the only thing this little HTT/LDT thing is...is your memory controller's communication speed. Look at your motherboard, and you see...there's no northbridge! Well...not like there was anyway hehe...the NB was the memory to cpu communication point. That is now integrated into the cpu itself.

 

All that HTT is, is the rate at which incoming memory meets cpu instructions...but if it is not running at optimal speed, then you start wondering why some super clock is not showing the good numbers, or isnt stable, or wont even boot haha.

 

so we'll break it down a little more ..

 

You take your NF2 AthlonXP 2500+ unlocked (default of 166x11) to 260x10...2600Mhz...with a bus speed of 520Mhz DDR (260x2). 10 Multi gives us 2600Mhz total.

 

Now lets take your NF3 A64 2800+ (default of 200x9) to 260x10...well, we can't right off because they won't go higher multiplier, only lower multiplier.

 

So we'll stick with x9 then, as we want to try and max out mhz along with FSB (which is misleading...FSB is normally used for cpu-to-northbridge speed...but these cpu's have a 'northbridge' built onto them and need no northbridge...So in theory if you had 1800Mhz Ram and 1800Mhz cpu...you get the idea lol).

 

So lets go 260x9. 2340Mhz or thereabouts. Great. But what is our HTT speed? Why, it is 2080Mhz...or 260Mhz, which is 520Mhz DDR, times 4 as that is the default HTT (LDT) multplier for these cpu's .

 

260x2 = 520Mhz DDR (just like the NF2!)

520Mhz x4, the cpu's HTT default multiplier, = 2080Mhz.

 

whoa...much much too high maybe...defintely above that 1800 unwritten limit...might be stable up here, but might not be stable.

 

so lets say we got some killa RAM and can do 280FSB on both the NF2 and NF3

 

NF2 would be as follows (which we should all know!)

 

280FSB x2 = 560Mhz DDR

 

if we can only reach 2600Mhz, then we have to lower the multi a little on the AthlonXP...so lets lower it to 280x9.5, which still gives us about 2660Mhz...we'll call it stable or we'll drop to 280x9 and live with 2520Mhz (and maybe crank up to 287x9 for a total of 2583Mhz.

 

AM I LOSING YOU YET?

 

now what about the A64?

 

280x2 = 560Mhz DDR times 4x HTT multi = 2240Mhz HTT

 

280x9 (cpu default mutliplier) = 2520Mhz...no problem...

 

but

 

its not stable!

 

the HTT bus is too high...lets drop it down to 3x HTT...

 

280x2 = 560Mhz DDR time 3x HTT = 1680Mhz HTT

 

now we get back in the '1200-1800' range. Much more stable as we know our A64 will max Mhz @ 2660 for example just like the AthlonXP.

 

so now that HTT speed is within reason, we do the Mhz calculation, just like we do on teh AthlonXP:

 

280x9 = 2520Mhz. Which is same as above. But this time the HTT is within reason and can function at this HTT speed.

 

1a. Overclocking the HTT bus.. Is it worth it ??

 

Below is two quotes from RGone that answer this question so good there really isnt much for me to say ..

Speeding HTT out of spec has about the same significance as 8 cars traveling the same direction on a 16 lane highway and you suddenly make the highway 20 lanes wide. It does not speed up anything. All 8 cars already had their own lane and adding lanes did nothing to speed up anything.
HTT which is a data bus has no problems toting the amount of data it is called on to tote. So it does not matter really how slow or fast you run it except that it will not bootup if too high or too low.

 

The memory does NOT transfer thru or over that bus so it has no bearing on Sandra memory bandwidth testing either. The memory talks directly to the cpu as the memory controller is there in the cpu. So for all practical purposes any discussion of HTT at the level of the 754 or 939 is mute and only needs be in a 'range' and that range must include enough to boot and not so high it does not boot.

Edited by Angry_Games

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2. Which bios is best for me?

 

This question is asked many times in forums and there is ONLY one correct answer.. Here is a quote from Angry_Games to answer this question..

There is no best bios. There is only a best bios for YOU.

 

You want to overclock? You had better be prepared with the right hardware, and even more, the right frame of mind. Overclocking is not just popping a rig together and cranking out 2750Mhz instantly.

 

Overclocking is a process that takes me (AG) anywhere from 3 days to 10 days to complete and verify that it is right and stable. I reboot my overclocking rigs about 500 times during this phase because I have a single (or multiple) setting(s) wrong and it has to be changed.

 

The worst part is when you finally get about 3-4 hours Prime95 stable, and then it fails...and you have to go back again and again and fiddle with one setting that you THINK might or might not be the cause of the problem, and then wait 3-4 seconds to find out it isn't Prime stable, or wait another 3-4 hours to find out that it is or is not.

 

 

The moral of this story is very clear.

 

Overclocking is not easy. Some of you might jump right in here and claim its the easiest thing in the world.

 

The thing is, I don't see but a couple of entries in the OC Database..and sure your rig might be overclocked and stable and you might not give a crap about the OC Database...but really, until you can pass all of those tests to where you have a legit entry for it, you aren't really stable.

 

And those entries I myself have put in there have required about a weeks worth of work on each one. Tweaking, rebooting, flashing, tweaking, rebooting, testing, rebooting, tweaking, testing testing testing testing.

 

RG and I sometimes shake our heads when we see guys that post about trying the new bios, and then post again an hour or two later claiming it just isn't stable...how can you possibly know if it is stable in an hour or two? How can you know if it is stable in a day even?

 

Honestly...you cannot.

 

Remember our saying that RG and I tell just about everyone that is new around here?

 

Just because your hardware worked on your last rig DOES NOT mean it will work like it did (if at all) on this new DFI rig

 

Well, overclocking follows that same rule...

 

Just because you could do 280x10 @ 2.5-3-7-4 on your previous bios does NOT mean you will find stability at those exact same settings on a different bios

 

That should be logical, since a bios changes settings within the bios....or else there wouldn't really be a need for a new bios right?

 

I think some of you guys are just impatient, and give us that 'i paid $2000 for this stuff and i expect it to be stable @ 2900Mhz right out of the box' and that just doesn't fly.

 

You paid $2000 or whatever for your hardware, but that doesn't mean you have an inkling of what it is capable of, nor how to get there 'right out of the box'.

 

RG and I have been doing this day in and day out for a couple of years (on DFI overclocking boards), and longer (just not as a job lol). When we got the new NF4, it took us...2 or 3 months to really figure out exactly what we had in our hands. And we are pretty experienced at this, and get to talk directly with Oskar and the engineers in Taiwan...so why would YOU expect to know everything possible about how these board perform and react right out of the box within the first day or two that you have them in your hands?

 

I have no doubt there are a lot of you that are much smarter and possibly better overclockers that Rgone and I...but that doesn't really mean diddly-squat when it comes to a new board like this that has an incredible amount of options and really has to be tweaked and tweaked and tweaked and tweaked to find what it likes...

 

A little patience is something that most are lacking, and I sincerely hope that if you ARE going to overclock, you have the foresight to take our bits of advice to heart:

 

Patience, logic, and then some more patience combined with hard work.

 

Rgone and I try very hard to show you guys the initial path to success...but it isn't up to us whether you succeed or not. It is up to you. We are here to guide you, and sometimes hold your hand...but beyond some guidance and a little hand holding, you are really on your own because your machine is yours, and even if we have the exact same hardware down to the exact same stepping/serial #'s, that doesn't mean we are going to get the same exact results as you, even if we supply you with the exact settings we used to achieve it.

 

I also want to clear up any confusion that anyone has with the different bios versions that are out ..( I.E.. -1,-2 and -3 )

 

-1 versions use romsip tables from the 3/26/05 bios

-2 versions use romsip tables from the 3/16/05 bios

-3 versions use romsip tables from the 3/10/05 bios

 

A romsip table is internal timings that are built into a bios.. Some configurations favor one romsip more then the other and this is why we have newer bios versions that use different romsips..

 

Rgone and Angry_Games have found that -2 versions are the best all-around bioses for all types of memory.. I also prefer the -2 versions whether im running bh5 or tcc5..

 

**Please Note**

If your using a revE cpu then you should be using bios 510 or newer to fully support your cpu.. Most boards are still shipping with 310 which will allow you to boot up and flash to a newer bios.. But before you start overclocking its recommended to update to one that will fully support your cpu.

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3. A64 Overclocking

 

First we are gonna go over most of the basic settings that you will find in an A64 motherboard BIOS. It

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This guide was written by johnrr6 with the help of the people he lists below..

So in no way do I take ANY credit for this awsome guide other then copy and pasting..

 

4. DFI NF4 BIOS Memory Guide

 

The purpose of this thread is to give you some kind of explanation and a good “start point” to the blizzard of available settings (especially memory) available on Oskar Wu’s fabulous NForce 4 motherboards from DFI. Especially to those who are new to the fun and excitement of overclocking. (I just love it when I can get my $200 chip to outperform a $500 chip). Unfortunately the manuals that are available for the board do a very poor job in this area, and we are all very leery of just doing a certain setting without some type of background information behind what the setting is/does. Having said that----some of these setting are VERY obscure and trying to find information on what they actually do is extremely difficult. Also, some of the below “explanations” may be totally unintelligible for the normal user (I know some were for me). Be that as it may, I’m a firm believer that SOME information is better than NO information. You may have to just dive in with some settings and use the time honored tradition of “try it before you buy it.”

 

BIG CAVEAT!!:

 

Please understand that this information and suggested settings may or may not work for you. Every user will usually have a different experience based upon his own equipment. The attempt here is to provide knowledge-----and hopefully get you in the ballpark! Also, my personal results were with Corsair BH-5 memory----there will be differences in how TCCD based memory should be set. There are definitely timing and voltage differences. Please always feel free to send me updated information to add to, or edit this thread!!

 

Very little of this information was created by me. I am simply acting as a “compiler and editor.” I will attempt to give credit to everyone whom I’m “borrowing” material from. If you are a contributor and are displeased by how I have used your materials just PM me and I will make amends.

 

Special Thanks to:

 

Adrian Wong and his RojakPot BIOS Explanation site

Adrian also has a fabulous BIOS book: Breaking Through the Bios Barrier

Lost Circuits

Tom’s Hardware Guide

AnandTech

Jess1313 and Samurai Jack, members of many forums, whose excellent guide I used as a true basis for this guide.

 

As well as the following contributors:

ABXZone: Sierra, Blue078, Eldonko, Xgman, Eva2000, HiJon89 (all members of many forums)

 

DFI-Street: RGone, AngryGames, masterwoot, Aurhinius

 

Xtrememsystems: kakaroto

 

Jess1313, Samurai Jack, Travis, bigtoe----who are also all members of many forums

 

Anand Tech: Wes Fink

 

First: A Very Brief Tutorial on RAM

 

Paraphrased from Tom’s Hardware guide:http://www.tomshardware.com/index.html

“To better understand how timing parameters affect memory performance, you should know about everything involved in accessing modern Random Access Memory (RAM). The "RAM Timings" chart below will give you an overview of how it works. The bottom line is a read process is initiated when the controller in the motherboard chipset selects the memory module that contains the data. (A64’s include the memory controller onboard). The controller addresses the right chip on the module and the data it holds. The cells of the chip are arranged in a matrix and are addressed using the row and column addresses. Each intersection represents one memory bit.

 

RamDiagram.JPG

 

Optimizing the timing parameters will speed up the processes involved in accessing RAM. The memory controller first determines the row address of the storage cell it intends to address. The column address is communicated once the time tRCD has transpired. The time tCL then passes while the data is transferred to the output register. The process can start all over again after waiting tRAS plus tRP.”

 

Here is a fabulous online multimedia explanation of RAM from Corsair: http://www.corsairmemory.com/memory_basics/153707/index.html

 

That is a very brief explanation----below is the guide….

 

But before you get started, here's a blank chart I made up to help your overclocking, or to just get stable settings on the NF4 boards----should apply for all versions. Got the idea from masterwoot. I edited his and made an updated version----thanks masterwoot!! Prints fine off of IE----set your margins to .5 inch both sides in page setup before you print----leave in "Portrait" mode. It may take a few seconds to load...

NF4 Memory & Voltages Bios Settings Chart

 

 

Additional Information on TCCD

 

A great Guide for TCCD memory only:

Kakaroto's TCCD Memory Guide

 

 

BIOS Optomization Guide for DFI NForce4 Motherboards:

 

Dram Frequency Set(Mhz)

 

Settings = 100(Mhz)(1/02), 120(Mhz)(3/05), 133(Mhz)(2/03), 140(Mhz)(7/10), 150(Mhz)(3/04), 166(Mhz)(5/06), 180(Mhz)(9/10), 200(Mhz)(1/01)

 

This is your “Divider” settings-----most people will argue that the best results come from Synchronous setup or 1:1, or in DFIs case, 1/01. All other settings are Asynchronous. You can use the little App called memFreq 1.1 to compute your memory speed using a divider. With a 1/01 ratio (Synchronous)----the formula with any 400 mghtz RAM is simple FSB (HTT) x 2 so if I you are running your FSB (HTT) at 240-----your DDR speed would actually be DDR480. You would possibly use a divider if you have weaker RAM to allow a higher CPU overclock.

 

Here’s another chart to help explain it from Travis at Vr-Zone who I believe had Oskar Wu’s help to develop it:

 

RamSpeed.JPG

 

Large Influence on Bandwidth----can be for Stability if using cheaper RAM that is maxed out at a 1:1 setting.

 

Suggested Setting for DFI: 200(Mhz)(1/01)

 

 

Command Per Clock(CPC)

 

Settings: Auto, Enable(1T), Disable(2T)

 

Command Per Clock(CPC) is also called Command Rate. It may be best in some instances to Disable (2T) w/ 2x512 RAM modules. It has a large Influence on Bandwidth/Stability.

 

From Adrian Wong’s site: http://www.rojakpot.com/

“This BIOS feature allows you to select the delay between the assertion of the Chip Select signal till the time the memory controller starts sending commands to the memory bank. The lower the value, the sooner the memory controller can send commands out to the activated memory bank. When this feature is enabled, the memory controller will only insert a command delay of one clock cycle or 1T. When this feature is disabled, the memory controller will insert a command delay of two clock cycles or 2T. The Auto option allows the memory controller to use the memory module's SPD value for command delay. If the SDRAM command delay is too long, it can reduce performance by unnecessarily preventing the memory controller from issuing the commands sooner. However, if the SDRAM command delay is too short, the memory controller may not be able to translate the addresses in time and the "bad commands" that result will cause data loss and corruption. It is recommended that you try enabling SDRAM 1T Command for better memory performance. But if you face stability issues, disable this BIOS feature."

 

Large Influence on Bandwidth/Stability.

 

Suggested Setting for DFI: Enable 1T whenever possible

 

 

CAS Latency Control(tCL)

 

Settings = Auto, 1, 1.5, 2, 2.5 3, 3.5, 4, 4.5.

 

This is the first timing that most ram companies rate their ram with. For example, you might see RAM rated at 3-4-4-8 @275mhz. this is the 3, in that situation. 2 yields the best performance, CAS 3 usually gives better stability. Please note; if you have Winbond-BH-5/6, you may not be able to use CAS3.

 

From Lost Circuits: http://www.lostcircuits.com/

“CAS is Column Address Strobe or Column Address Select. CAS controls the amount of time (in cycles (2, 2.5,& 3) between receiving a command and acting on that command. Since CAS primarily controls the location of HEX addresses, or memory columns, within the memory matrix, this is the most important timing to set as low as your system will stably accept it. There are both rows and columns inside a memory matrix. When the request is first electronically set on the memory pins, the first triggered response is tRAS (Active to Precharge Delay). Data requested electronically is precharge, and the memory actually going to initiate RAS is activation. Once tRAS is active, RAS, or Row Address Strobe begins to find one half of the address for the required data. Once the row is located, tRCD is initiated, cycles out, and then the exact HEX location of the data required is accessed via CAS. The time between CAS start and CAS end is the CAS latency. Since CAS is the last stage in actually finding the proper data, it's the most important step of memory timing.”

 

From Adrian Wong’s site: http://www.rojakpot.com/

“This BIOS feature controls the delay (in clock cycles) between the assertion of the CAS signal and the availability of the data from the target memory cell. It also determines the number of clock cycles required for the completion of the first part of a burst transfer. In other words, the lower the CAS latency, the faster memory reads or writes can occur. Please note that some memory modules may not be able to handle the lower latency and may lose data. Therefore, while it is recommended that you reduce the SDRAM CAS Latency Time to 2 or 2.5 clock cycles for better memory performance, you should increase it if your system becomes unstable. Interestingly, increasing the CAS latency time will often allow the memory module to run at a higher clock speed. So, if you hit a snag while overclocking your SDRAM modules, try increasing the CAS latency time.”

 

Slight Influence on Bandwidth / Large Influence on Stability.

 

Suggested Settings for DFI: 1.5, 2, 2.5, and 3. (Lower = Faster)

 

 

RAS# to CAS# Delay(tRCD)

 

Settings = Auto, 0, 1, 2, 3, 4, 5, 6, 7.

 

This is the second timing that most ram companies rate there ram with. For example, you might see ram rated at [email protected] This is the first 4, in that situation.

 

From Adrian Wong’s site: http://www.rojakpot.com/

”This BIOS feature allows you to set the delay between the RAS and CAS signals. The appropriate delay for your memory module is reflected in its rated timings. In JEDEC specifications, it is the second number in the three or four number sequence. Because this delay occurs whenever the row is refreshed or a new row is activated, reducing the delay improves performance. Therefore, it is recommended that you reduce the delay to 3 or 2 for better memory performance. Please note that if you use a value that is too low for your memory module, this can cause the system to be unstable. If your system becomes unstable after you reduce the RAS-to-CAS delay, you should increase the delay or reset it to the rated delay. Interestingly, increasing the RAS-to-CAS delay may allow the memory module to run at a higher clock speed. So, if you hit a snag while overclocking your SDRAM modules, you can try increasing the RAS-to-CAS delay.”

 

Large Influence on Bandwidth/ Stability.

 

Suggested Settings for DFI: 2-5 ----2 yields the best performance, and 4-5 yields the best over clock (5 is usually overkill). Usually cheaper RAM will not be able to use 2, and reach their max OC. (Lower = Faster)

 

 

Min RAS# Active Timing(tRAS)

 

Settings = Auto, 00, 01, 02, 03, 04, 05, 06, 07, 08, 09, 10, 11, 12, 13, 14, 15.

 

This is the fourth timing that most ram companies rate there ram with. For example, you might see ram rated at 3-4-4-8 @275mhz. this is the 8, in that situation.

 

From Adrian Wong’s site: http://www.rojakpot.com/

”This BIOS feature controls the memory bank's minimum row active time (tRAS). This constitutes the time when a row is activated until the time the same row can be deactivated. If the tRAS period is too long, it can reduce performance by unnecessarily delaying the deactivation of active rows. Reducing the tRAS period allows the active row to be deactivated earlier. However, if the tRAS period is too short, there may not be enough time to complete a burst transfer. This reduces performance and data may be lost or corrupted. For optimal performance, use the lowest value you can. Usually, this should be CAS latency + tRCD + 2 clock cycles. For example, if you set the CAS latency to 2 clock cycles and the tRCD to 3 clock cycles, the optimum tRAS value would be 7 clock cycles. But if you start getting memory errors or system crashes, increase the tRAS value one clock cycle at a time until your system becomes stable.”

 

It appears throughout the web that this is a much debated timing. Some may argue that 00, 05, or 10 is the faster/most stable. There probably isn’t a right answer for this one, it all depends on your ram. If you need a good starting point, usually most/all ram can achieve their max OC on 10 tRAS, even if one of the other settings is faster.

 

Slight Influence on Bandwidth/Stability.

 

Suggested Settings for DFI: Suggest you use only 00, and 5-10. I’d start with 8 and play around from there. (Lower = Faster)

 

 

Row Precharge Timing(tRP)

 

Settings = Auto, 0, 1, 2, 3, 4, 5, 6, 7

 

This is the third timing that most ram companies rate there ram with. For example, you might see ram rated at 3-4-4-8 @275mhz. this is the second 4, in that situation.

 

From Adrian Wong’s site: http://www.rojakpot.com/

”This BIOS feature specifies the minimum amount of time between successive ACTIVATE commands to the same DDR device. The shorter the delay, the faster the next bank can be activated for read or write operations. However, because row activation requires a lot of current, using a short delay may cause excessive current surges. For desktop PCs, a delay of 2 cycles is recommended as current surges aren't really important. The performance benefit of using the shorter 2 cycles delay is of far greater interest. The shorter delay means every back-to-back bank activation will take one clock cycle less to perform. This improves the DDR device's read and write performance. Switch to 3 cycles only when there are stability problems with the 2 cycles setting.”

 

Large Influence on Bandwidth/Stability.

 

Suggested Settings for DFI: 2-4 ----2 yields the best performance, and 4-5 yields the best stability when overclocking (5 is usually overkill). A lot of RAM will not be able to use 2, and reach their max OC. (Lower = Faster)

 

 

Row Cycle Time(tRC)

 

Settings = Auto, 7-22 in 1.0 increments.

 

From Adrian Wong’s site: http://www.rojakpot.com/

”This BIOS feature controls the memory module's Row Cycle Time or tRC. The row cycle time determines the minimum number of clock cycles a memory row takes to complete a full cycle, from row activation up to the precharging of the active row. Formula-wise, the row cycle time (tRC) = minimum row active time (tRAS) + row precharge time (tRP). Therefore, it is important to find out what the tRAS and tRP parameters are before setting the row cycle time. If the row cycle time is too long, it can reduce performance by unnecessarily delaying the activation of a new row after a completed cycle. Reducing the row cycle time allows a new cycle to begin earlier. However, if the row cycle time is too short, a new cycle may be initiated before the active row is sufficiently precharged. When this happens, there may be data loss or corruption. For optimal performance, use the lowest value you can, according to the tRC = tRAS + tRP formula. For example, if your memory module's tRAS is 7 clock cycles and its tRP is 4 clock cycles, then the row cycle time or tRC should be 11 clock cycles. However, if the row cycle time is too short, a new cycle may be initiated before the active row is sufficiently precharged. When this happens, there may be data loss or corruption.”

 

Large Influence on Bandwidth/Stability.

 

Suggested Settings for DFI: 7 yields the best performance, 15-17 yields the best stability/over clock. 22 is way overkill. Start at 16, and work your way down from there. 7 is usually much too tight for most average ram. Remember the tRC = tRAS + tRP formula. (Lower = Faster)

 

 

Row Refresh Cycle Time(tRFC)

 

Settings = Auto, 9-24 in 1.0 increments.

 

From the DFI BIOS: “This bios setting represents time to refresh a single row on the same bank of memory. This value is also the time interval between a refresh (REF command) to another REF command to different rows of the same bank. The tRFC value is higher than tRC as column access gates are not turned on during it’s issue.”

 

Large Influence on Bandwidth/Stability.

 

Suggested Settings for DFI: 9 is usually unreachable and 10 yields the best performance. 17-19 yields the best stability/over clock with 19 probably overkill. Start at 17 and work your way down. Most stable timing is usually set to 2-4 clocks higher than tRC. (Lower = Faster)

 

 

Row to Row Delay(also called RAS to RAS delay)(tRRD)

 

Settings = Auto, 0-7 in 1.0 increments.

 

From Adrian Wong’s site: http://www.rojakpot.com/

“This BIOS feature specifies the minimum amount of time between successive ACTIVATE commands to the same DDR device. The shorter the delay, the faster the next bank can be activated for read or write operations. However, because row activation requires a lot of current, using a short delay may cause excessive current surges. For desktop PCs, a delay of 2 cycles is recommended as current surges aren't really important. The performance benefit of using the shorter 2 cycles delay is of far greater interest. The shorter delay means every back-to-back bank activation will take one clock cycle less to perform. This improves the DDR device's read and write performance. Switch to 3 cycles or higher only when there are stability problems with the 2 cycles setting.”

 

Slight Influence on Bandwidth/Stability.

 

Suggested Settings for DFI: 00 yields the best performance and 4 yields the best stability/over clock (anything above 4 is probably overkill). 2 is probably your best bet. 00 sounds odd, but it has worked well for others, even at 260 MHz. (Lower = Faster)

 

 

Write Recovery Time(tWR)

 

Settings = Auto, 2, 3.

 

From Adrian Wong’s site: http://www.rojakpot.com/

“This BIOS feature controls the Write Recovery Time (tWR) of the memory modules. It specifies the amount of delay (in clock cycles) that must elapse after the completion of a valid write operation, before an active bank can be precharged. This delay is required to guarantee that data in the write buffers can be written to the memory cells before precharge occurs. The shorter the delay, the earlier the bank can be precharged for another read/write operation. This improves performance but runs the risk of corrupting data written to the memory cells. It is recommended that you select 2 Cycles if you are using DDR200 or DDR266 memory modules and 3 Cycles if you are using DDR333 or DDR 400 memory modules. You can try using a shorter delay for better memory performance but if you face stability issues, revert to the specified delay to correct the problem.”

 

Slight Influence on Bandwidth/Stability.

 

Suggested Settings for DFI: 2 yields better performance, and 3 yields better stability/over clock. (Lower = Faster)

 

 

Write to Read Delay(tWTR)

 

Settings: Auto, 1, 2

 

From Adrian Wong’s site: http://www.rojakpot.com/

”This BIOS feature controls the Write Data In to Read Command Delay (tWTR) memory timing. This constitutes the minimum number of clock cycles that must occur between the last valid write operation and the next read command to the same internal bank of the DDR device. The 1 Cycle option naturally offers faster switching from writes to reads and consequently better read performance. The 2 Cycles option reduces read performance but it will improve stability, especially at higher clock speeds. It may also allow the memory chips to run at a higher speed. In other words, increasing this delay may allow you to overclock the memory module higher than is normally possible. It is recommended that you select the 1 Cycle option for better memory read performance if you are using DDR266 or DDR333 memory modules. You can also try using the 1 Cycle option with DDR400 memory modules. But if you face stability issues, revert to the default setting of 2 Cycles.”

 

From the DFI BIOS: “This Bios setting specifies the write to read delay. Samsung calls this TCDLR (last data in to read command). It is measured from the rising edge and following the last non-mask data strobe to the rising edge of the next read command. JDEC usually specifies this as one clock.”

 

Slight Influence on Bandwidth/Stability.

 

Suggested Settings for DFI: 1 yields better performance, and 2 yields better stability/over clock. (Lower = Faster)

 

 

Read to Write Delay(tRTW)

 

Settings = Auto, 1-8 in 1.0 increments.

 

Paraphrased From Adrian Wong’s site: http://www.rojakpot.com/

”When the memory controller receives a write command immediately after a read command, an additional period of delay is normally introduced before the write command is actually initiated. As its name suggests, this BIOS feature allows you to skip (or raise) that delay. This improves the write performance of the memory subsystem. Therefore, it is recommended that you enable this feature for faster read-to-write turn-arounds. However, not all memory modules can work with the tighter read-to-write turn-around. If your memory modules cannot handle the faster turn-around, the data that was written to the memory module may be lost or become corrupted. So, when you face stability issues, disable (or raise the value) of this feature to correct the problem.”

 

From the DFI BIOS: “This field specifies the read to write delay. This is not a DRAM specified timing parameter, but must be considered due to the routing latencies on the clock forwarded bus. It is counted from the first address bus slot which was not associated with part of the read burst.”

 

Slight Influence on Bandwidth/Stability.

 

Suggested Settings for DFI: 1 yields better performance, and 4 yields better stability/over clock (4 is overkill). Recommend try 1 and move to 2 if unstable. (Lower = Faster)

 

 

Refresh Period(tREF)

 

Settings = Auto, 0032-4708 in variable increments.

 

1552= 100mhz(?.?us)

2064= 133mhz(?.?us)

2592= 166mhz(?.?us)

3120= 200mhz(?.?us)(seems to be a/ Bh-5,6 sweet spot at 250+mhz)

---------------------

3632= 100mhz(?.?us)

4128= 133mhz(?.?us)

4672= 166mhz(?.?us)

0064= 200mhz(?.?us)

---------------------

0776= 100mhz(?.?us)

1032= 133mhz(?.?us)

1296= 166mhz(?.?us)

1560= 200mhz(?.?us)

---------------------

1816= 100mhz(?.?us)

2064= 133mhz(?.?us)

2336= 166mhz(?.?us)

0032= 200mhz(?.?us)

---------------------

0388= 100mhz(15.6us)

0516= 133mhz(15.6us)

0648= 166mhz(15.6us)

0780= 200mhz(15.6us)

---------------------

0908= 100mhz(7.8us)

1032= 133mhz(7.8us)

1168= 166mhz(7.8us)

0016= 200mhz(7.8us)

---------------------

1536= 100mhz(3.9us)

2048= 133mhz(3.9us)

2560= 166mhz(3.9us)

3072= 200mhz(3.9us)

---------------------

3684= 100mhz(1.95us)

4196= 133mhz(1.95us)

4708= 166mhz(1.95us)

0128= 200mhz(1.95us)

 

Paraphrased From Adrian Wong’s site: http://www.rojakpot.com/

”This BIOS feature allows you to set the refresh interval of the memory chips. There are (several) different settings as well as an Auto option. If the Auto option is selected, the BIOS will query the memory modules' SPD chips and use the lowest setting found for maximum compatibility. For better performance, you should consider increasing the Refresh Interval from the default values (15.6

Edited by Angry_Games

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Please discuss in this thread, and please patiently await the DIY-Street team to begin tackling this guide to update it not only for current AMD hardware, but we will begin to integrate the Intel overclocking aspects as well (or make a completely separate guide).

 

This information is still valid for a pretty big chunk of users, but it is getting outdated.

 

Again, now that we have merged with OCC, our team will begin working on a new, updated OC Guide for you to enjoy (or curse at, take your pick!).

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I was wondering how long it'd be before this particular guide made it across. Excellent piece of work, I must say.

 

However, if you are creating guides for newer architecture, I would think new guides would be a good idea, rather than shoehorning into this one - people might get a bit lost!

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So after we port over some of the other threads this guide will have lots of links to be amended, let me know if you need help doing that. I see a lot of DFI-Street links that are still redirecting to DIY.

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I was wondering how long it'd be before this particular guide made it across. Excellent piece of work, I must say.

 

However, if you are creating guides for newer architecture, I would think new guides would be a good idea, rather than shoehorning into this one - people might get a bit lost!

it won't be shoehorning since all of the current AMD64 platforms still rely very much on a lot of this information. AM2 is only slightly different (with DDR2/3), and Phenom is probably a bit different (will know if someone gives me a Phenom). Intel is also still relying a lot on the information here. We will get together and decide which avenue would be the best approach.

 

edit: Reel the links should redirect without issue just like they did when we changed from dfi-street to diy-street. We will of course try to make sure all links work once the diy-street forum is down permanently and being integrated into this one.

 

mods/admins: at some point we'd like to get rid of all posts other than ones pertinent to this thread so that anyone wanting to ask questions or make comments won't have to sift through staff conversation. I'll let you know when we are done editing this thing.

 

Street staff: please check through this and give me info as to which links etc need to be changed and I'll take care of it until we get some more of us with mod permissions to edit each other's work.

 

ok, dinner time at a hole-in-the-wall mexican place! (freaking 9 lbs of grease on a plate of nachos and soooooo good...)

Edited by Angry_Games

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it won't be shoehorning since all of the current AMD64 platforms still rely very much on a lot of this information. AM2 is only slightly different (with DDR2/3), and Phenom is probably a bit different (will know if someone gives me a Phenom). Intel is also still relying a lot on the information here. We will get together and decide which avenue would be the best approach.

 

edit: Reel the links should redirect without issue just like they did when we changed from dfi-street to diy-street. We will of course try to make sure all links work once the diy-street forum is down permanently and being integrated into this one.

 

mods/admins: at some point we'd like to get rid of all posts other than ones pertinent to this thread so that anyone wanting to ask questions or make comments won't have to sift through staff conversation. I'll let you know when we are done editing this thing.

 

Street staff: please check through this and give me info as to which links etc need to be changed and I'll take care of it until we get some more of us with mod permissions to edit each other's work.

 

ok, dinner time at a hole-in-the-wall mexican place! (freaking 9 lbs of grease on a plate of nachos and soooooo good...)

 

Sorry, I should've been clearer in that I meant about Intel Core 2 etc :blush: I teh n00b!

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Sorry, I should've been clearer in that I meant about Intel Core 2 etc :blush: I teh n00b!

 

 

we can take the info already here in the forums in the overclocking threads and build a Intel C2D/Q guide...

 

Most of us (some of us) have a C2D/Q and can help get one laid down to good ground....I myself just got a Q6700 and will be working on it greatly...

 

But with current boards coming out and better bios revisions people wont need to rely on guides as much as yesteryears...some just clock as well as others leaving options on Auto...;)

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