Ram Matched to CPU?

[cdgtcc]

Hey guys. First time here. I tried searching the forums first but couldn't find anything related to my question. Here goes. When building a PC and choosing RAM, I always went with the rule of matching the FSB of the CPU to your RAM. For instance my Core 2 duo has 800mhz fsb, so i matched it with DDR2 800. Now if my CPU FSB was 1333, I would match it with DDR3 1333. Is this a correct assumption? I always went with this rule, but now am questioning it since after checking out Alienware, I noticed they are using the DDR2800 for nearly every Intel CPU they offer. So whats the verdict? Am I just wasting money on the faster ram? Or is this rule i've always followed correct? Thanks in advance!

 

[HyperBladeST]

Here's how it works :

DDR2 400 (2*200 Mhz) => FSB 800 (4*200 Mhz)
DDR2 533 (2*266 Mhz) => FSB 1066 (4*266 Mhz)
DDR2 667 (2*333 Mhz) => FSB 1333 (4*333 Mhz)
DDR2 800 (2*400 Mhz) => FSB 1600 (4*400 Mhz)
DDR2 1066 (2*533 Mhz) => FSB 2132 (4*533 Mhz)
and so on
...
I suggest that you crank your FSB to 1600 (probably 400 in BIOS) to match you RAM speed or you can always run your DDR2 800 at 667 Mhz.

I hope I explained it correctly

 

[cdgtcc]

Sort of. So currently i run a core 2 duo. regular 800 mhz fsb. and my ram is DDR2800. so ram runs half of cpu fsb? so i can set the fsb to 1600?