FSB confusion

DeathStalker · 3 Sep 2007 at 11:15

Noob question, sorry. :confused:

I have a Gigabyte GA_P35C_DS3R motherboard which I chose because it supports cpu FSB up to 1333, and I'm planning on fitting a Core 2 Quad cpu into it. I haven't got any memory for it yet, but having read the manual for the mobo, it says that ddr2 memory is supported at 800/667 FSB. Would I get any extra benefit buying memory that has 1066, or would I be better going for 800MHz memory?

semi-pro waster · 3 Sep 2007 at 11:31

Any Ram that is PC5300 (667mhz with a 333mhz actual) or above would be fine for a 1333mhz CPU at stock speeds, if you want to overclock then you should be thinking about PC6400 (800mhz with a 400mhz actual) or PC8500 (1066mhz with a 533mhz actual). I'd probably go with PC6400 unless you are thinking about trying for fairly hefty overclocks. Hopefully that is clear but if not just ask.

DeathStalker · 3 Sep 2007 at 11:41

Thanks for that. I might think about overclocking once I've got it running, but not too high. The PC6400 is a bit cheaper too, so I might get 4Gb of that.

misterPK · 3 Sep 2007 at 11:43

Am I right in saying it only supports that hgh a FSB because it can take DDR3 RAM? This isnt really my area as I've never ventured into overclocking, but I've been looking at getting this board for a future upgrade.

PK!

semi-pro waster · 3 Sep 2007 at 11:57

It supports that high an FSB because that is the new FSB speed of Intels latest CPUs, previously it was more common to have 1066mhz or some of the lower CPUs in the range are 800mhz.

misterPK · 3 Sep 2007 at 12:07

Hmm, looks like I still have some learning to do then!

PK!

Admiral Huddy · 3 Sep 2007 at 15:50

misterPK said:
Hmm, looks like I still have some learning to do then!

PK!

Give this a read.. it may help

http://www.huddysworld.co.uk/Techpages/PCZone_TechieTalk_1.shtml

Energize · 3 Sep 2007 at 16:30

It's simple once you understand it.

Say you have an fsb of 1333MT/s, since Intel cpus are quad pumped the fsb is 333.25MHz. DDR2 memory has the bus running at 2x the speed of the memory chips, so DDR667 chips are running at 333.5MHz. But because DDR2 ram is dual pumped DDR667 ram runs at an fsb of 1333MT/s also. So it provides exactly enough bandwidth for the cpu.

Say the cpu has a multi of 8x you divide the cpu clock speed you want by 8 to get the fsb you need to run at, say you need to run the fsb at 500MHz, you need DDR2 1000 ram.

However you can just run the ram in dual channel mode and use a divider, that way the ram only needs to run at half the fsb of the cpu to achieve the same performance.