Quick question about memory dividers...

[Ichigo]

For example, if I have DDR2 667Mhz memory but I want to run a 400Mhz FSB, can I set something like a 5:6 divider or is that not possible?

 

[brencat]

No, there is no divider less than 1:1. But what you're really asking is, will my memory run faster than spec? Answer: Yes, with a little more voltage.

In your example, DDR2-667 means 333 FSB (i.e. 333 x 2 (double-data rate)). Now if you had a CPU like an E8400 that you were planning to OC to 400 x 9 (3.6 ghz), you would have to OC your RAM to run it in sync with the processor FSB of 400. Most RAM can do this no problem with a tad extra DDR2 voltage (vDIMM). In that case, you would want to set the divider to run 1:1 with the processor.

You would only run a RAM divider higher than the CPU FSB in cases where the CPU FSB was less than the spec speed of the RAM.

Look at my sig...I run an E2180 @ 3.2ghz (320 FSB x 10 multi). My RAM is DDR2-800 spec so that means 400 FSB spec. Since my CPU FSB is 320 and my RAM spec is 400, I can run my RAM at 1:1 (320) or use a higher divider like (4:5) which lets the RAM run at 400 (i.e. 320/4 x 5). I've chosen to OC the RAM even higher with a 2:3 divider so that means my RAM is running at 320/2 x 3 = 480mhz relative to my CPU FSB of 320mhz.

 

[rogue1979]

Yes, if you are running an AMD set up.

Just checked my Biostar G31 M-7 TE and my Asrock Conroe 1333 and both of them
offer a lower memory divider at 333MHz fsb, allowing either 667 for 1/1 or 533.

Hmm, I always heard you couldn't run less than 1/1 with C2D, but guess I was wrong.