Can't get my head around DDR2 + Intel. Can people help explain?

[Firegod]

Hello all.

I've been doing some reading and searching on the forum but seem to be getting in a muddle about how DDR2 speeds/ratings and Intel CPU's fit together. (Damn my A64+DDR is so easier to understand!).

What I can work out is that basically:-

PC2-5300 = 667Mhz
PC2-6400 = 800Mhz
PC2-8500 = 1066Mhz

Now, Intel CPU's. I keep hearing that they quad-pump the FSB to give them their 1066Mhz FSB. So a bit of maths means that actually, the FSB of the Intel CPU is 266Mhz? Is that correct?

However, as it stands, to run the CPU and Memory in a 1:1 ratio you need PC2-8500 memory. As the CPU FSB = 1066Mhz and the Memory = 1066Mhz?

So my question being, why is PC2-6400 (800Mhz) seen to be enough. Surely it's running slower? (Ignoring overclocking at the moment to keep things very simple for me. lol).

Thanks for any help in clearing this up for me. Diagrams and simple colouring in's most welcome.

 

[Firegod]

Thanks guys, I think I start to get it!

So the 1066Mhz CPU's are actually just 266Mhz. Obviously, double for DDR which makes 533Mhz. In other words, you need PC2-4200 Memory.

Therefore, when overclocking, PC2-6400 is more than enough (I guess you could argue that PC2-5400 would be ok for a small overclock?)

However, the newer CPU's for example with 1600Mhz would have an FSB of 400Mhz and therefore, DDR means it is 800Mhz. Therefore needing PC2-6400 Memory, but to overclock you should get PC2-8500.

Does that seem to make sense? I think I can see why PC2-6400 is enough!

 

[Firegod]

That's spot-on

Yey. Lol.