RAM speed compared to FSB speed?

bigG · 17 Jun 2008 at 21:07

Hi all,

i'm sorry if this has already been answered, but i'm not very clued up on the technical side of computers.

I was wondering when you choose a CPU with an FSB of 800mhz does the ram speed have to match this? e.g pc2-6400 (800mhz).

thanks

semi-pro waster · 17 Jun 2008 at 21:26

I'll just explain it briefly for Intels as that is what I'd assume you are talking about. Intel CPUs are currently quad-pumped in effect so to get a FSB speed of 800mhz you need Ram capable of 200mhz actual e.g. PC3200 speeds but it will be DDR2 normally and since that isn't common you just buy PC4200 (267mhz) or PC5300 (333mhz)*, for a 1066mhz FSB you need PC4200 as a minimum (4*267=1066mhz or near enough). Getting faster Ram can mean you are paying extra for no real reason but it will underclock fine usually and gives you more headroom for overclocking. For the current CPUs it is a shame not to overclock and I wouldn't generally suggest anything lower than PC5300 or PC6400 given it is so cheap.

*nb as it is DDR2 it will be labelled as 533mhz for PC4200 or 667mhz for PC5300, 800mhz for PC6400 etc etc.

bigG · 17 Jun 2008 at 21:54

Thankyou that is much clearer. I think!

bigG · 17 Jun 2008 at 22:07

Lets see if i understand,

if i bought the E8200 with an FSB of 1333mhz, i would use pc-5300 as a minimum

semi-pro waster · 17 Jun 2008 at 22:09

Yep that would be the minimum you'd need, most people would go with PC6400 though to give them a little bit extra headroom and the price difference is negligible. You could go for PC8000/8500 if you wanted to overclock further but that is up to you.

bigG · 18 Jun 2008 at 08:25

Thanks for the help