Conroe -- DDR2 Help (Big Noob)

[calledminime]

Hi everyone,

 

I am planning on buying a C2D E6600 but I've never used DDR2 RAM before and am quite confused on how it works -- I've always had an Athlon system till now and so I have no idea how overclocking is different on an Intel system.

 

What is really confusing to me is DDR2 speeds:

 

PC2-3200: DDR2-SDRAM memory stick specified to run at 200 MHz using DDR2-400 chips

PC2-4200: DDR2-SDRAM memory stick specified to run at 266 MHz using DDR2-533 chips

PC2-5300: DDR2-SDRAM memory stick specified to run at 333 MHz using DDR2-667 chips

PC2-6400: DDR2-SDRAM memory stick specified to run at 400 MHz using DDR2-800 chips

 

1) On my AMD system, the default FSB was 200; but is the default speed on Intel CPUs 266? That is the only way I could figure that the e6600 could clock to its standard 2400MHz.

 

2) How does DDR2 RAM work on an Intel system? If the default FSB is indeed 266, then should I go with PC2-4200 which also runs at that speed? What would be the purpose of getting DDR2-800 then? Since DDR2-800 runs at 400MHz does that mean that I if I could raise my FSB to 400 it would run in sync? Also, why would I get DDR2-1067 RAM?

 

3) Could you briefly describe the relationship of the FSB of the CPU and the RAM and how each are affected by one another? For example, in the screenshot below:

 

 

I see that the e6600's FSB has been increased to 371; yet the frequency on the RAM, with the dividers, is at 278--is this, based on the DDR2 above, really running at 556MHz (278*2)?

 

Thanks in advance for the help. I really want to get an understanding of how things work before I go and purchase my system.

 

Thanks again.

[davidhammock200]

Lots of answers at Anandtech.

 

http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=2795

 

http://www.anandtech.com/mb/showdoc.aspx?i=2797

 

http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=2802

 

http://www.anandtech.com/memory/showdoc.aspx?i=2809

 

Good reading,

Dave

[red930]

Overclocking is essentially the same, up the FSB and the memory speed goes up with it, so people wanting 400+ FSB are going to probably want memory that can go 1:1 with the FSB, so DDR2 800 and DDR2 1000 exist. Same reason we generally get DDR500 instead of DDR400 on our AMD 939/754 systems.

[calledminime]

Thanks for the links davidhammock200 but I've actually already looked at them. The articles themselves don't really go into too much detail about the various speeds, at least not from what I read. They just say that high performance RAM is good and that DDR21067 would be noticeable and worth the money.

 

I'm still just a little uncertain as to how the chart below related:

 

How exactly do they come up with the values for DDR2400? What FSB is the CPU at so that the divider will work out that way?

 

Sorry again for my lack of knowledge, but I really appreciate everyone's help.

 

So for example, DDR2 800 is really rated to run at a FSB of 400, while DDR2 667 is for 333?

[red930]

So for example, DDR2 800 is really rated to run at a FSB of 400, while DDR2 667 is for 333?

 

Not necessarily at an FSB of 400, but if there's no divider (i.e. it's 1:1) then yes. Apparently positive dividers work fairly well for DDR2, so if your board or cpu can't handle the speed your memory could, you can use those to increase the memory speed.

 

I disagree with noticing the speed of DDR2 1067...sure it'd be nice but to actually BUY that is expensive as hell, I'm sure you've seen the prices. However, DDR2 800 can be had for a pretty reasonable price, and if you read reviews on current ram you'll see a lot hit DDR2 1000+ anyways.

 

Of course this is just giving you more options when overclocking, hopefully negating the need for a divider (just for ease of use and all), and of course giving you a little more performance as well.

 

Edit: that might have been a little confusing, so yes, DDR2 800 is rated at 400 mhz, DDR2 1000 at 500, and so on. Stock FSB (depending on the processor) is going to be 266 Mhz, so you need at least DDR2 533 to run at stock speeds.

[naddie]

I asked the same question and came to my own conclusion. Hope it helps you (especially if you understand numbers more than verbal explainations).

 

http://www.dfi-street.com/forum/showthread.php?t=62901