Memory Timings

[mugenoel]

What would be Faster DDR400 on 2-2-2-5 or DDR500 on 2.5-3-3-7??

[Surrept]

The best way to overcome loose timeings is through higher fsb. A system with tight timeings will take fewer clocks to make a transaction while a looser system will take more cycles per transaction but will return more cycles over a given amount of time.

 

Say tight timeings takes 10 cycles to complete a read/write and your operating at 60 cycles a minute, this would make for 6 transactions per minute. Now say you take 15 cycles per transaction but now your operating at 120 cycles per minute, now your makeing 8 transactions per minute.

 

Theres a slew of other factors when figureing a systems properties

 

One factor that may play in here is a sort of instruction stepping where one command can begin while another command is being processed, this takes place inside the cpu/cache and i'm uncertain how timeings play into the cpu but i'm certain factors like this work into the ram end of things. bank interleaving comes to mind

[mugenoel]

so meaning that since mhz matters in athlon systems the ddr500 would be considerably faster?

[Sharp]

Hello,

 

The CPU running at 250Mhz FSB is going to be faster.

 

200Mhz = 5ns

250Mhz = 4ns

 

2 cycles @200Mhz = 10ns

2 cycles @200Mhz = 10ns

2 cycles @200Mhz = 10ns

5 cycles @200Mhz = 25ns

 

2.5 cycles @250Mhz = 10ns

3 cycles @250Mhz = 12ns

3 cycles @250Mhz = 12ns

7 cycles @250Mhz = 28ns

 

So in terms of only the memory/ data access / latencies have gone up a bit. (slower)

 

Really 2-2-2-5 @200Mhz translates to 2.5 - 2.5 - 2.5 - 6.25 @250Mhz.

[mugenoel]

wow....thats very informative......hmmm.....well my fsb is at 240 ryt now and im on a 5:6 multiplier....hmm very confised ryt now.......so iges i have to match the fsb to the mem speed correct?? the close they are the better??

[mugenoel]

my cpu is at 2.4 ryt now btw

[Sharp]

Having the CPU higher than the memory is ok providing that the CPU does not send more than (240FSB @5:6 = 200MEM) 3200MB/s.

 

As your board does not support Dual channel mode, 6400MB/s, you are causing a bottleneck.

 

at stock settings, 200Mhz, what memory scores do you get in Everest/sisoft sandra?

near 3200MB/s?

 

So if you want the best possible performance out of your overclock, run the memory @250Mhz too.

 

Your memory bandwidth scores should then go over 3200MB/s.

[Ubermann]

Bandwidth isnt that very important.

High CPU clock is where the gains are for most stuff you do on your computer.

Going from single channel to dual channel is like 3% average performance increase ?

Low timings and 200fsb is important. Below 200 you start to suffer.

[mugenoel]

how bout 2.5ghz on CPU and ddr500 on memory at 2.5-3-3-8??any good still doing sum benches to see if stable

[daglesj]

Well I have been running my 3500+ system with the following two setups -

 

1. 11x220 (2420Mhz) with 2-5-5-9 and all other settings at auto.

 

or

 

2. 9x250 (2250Mhz) with 2.5-5-5-9 HTT with 4x multi and other settings at auto.

 

All the benches have been fairly similar.

[Fire-N-Ice]

What would be Faster DDR400 on 2-2-2-5 or DDR500 on 2.5-3-3-7??

 

 

My opinion would be ddr500, and an opinion is all you can get here, since there is no 1 answer for everyone. Run benchmarks, do whatever you do on your computer (taking actual times of loading programs, etc) both ways, and you'll have your answer. CPU MHZ is king with these cpu's/boards. (By these I mean a NF4 board and using an AMD Athlon 64. The AMD 64's have the memory controller on it.

[mugenoel]

well i have tried to boot at 2.5-3-3-7 on 250 but i have to put he cpu on a 9x divider resulting at 2250 but.....CPU is lower but mem is higher.......CPU = King to therefore it would be better for me to 2400mhz and 200mhz on memory on 2-2-2-5......so thats is what i conclude.....thank you all for your support