General RAM Overclocking Questions

[giantpinkbunnyhead]

I know this is rather simple, but I guess I'm just looking for confirmation from the OC experts here.

I know that PC3200 Runs at about 200 MHz. (400 in dual, right?). But if I overclock the CPU, an Opty 165, this also OC's the RAM.

So lets say my opty CPU is at 278 x 9. (it is.) My RAM, being DDR400, doesn't like this so I've had to use a divider of 3/4 to bring the RAM speeds closer to "normal". Now would this be wholly unnecessary if I had, say, PC4000 RAM? Or similar? Is this what the "faster" RAM is for, so I can in theory keep a 1:1 divider with a solid CPU overclock?

I have heard that my mobo (DFI Ultra-D) supports up to PC3200. What would happen if I put faster RAM in there with an OC'd CPU? Would it still work?

 

[5t3v0]

You are right in pretty much everything you've said. Your board accepts any rated DDR ram, it only 'officially' supports PC3200 since the A64s only have a 200MHz clock. It will support PC4000 & PC4800 just as it would support PC2100 & PC2700.

2Gb kits aren't overclocking so well compared to 1Gb kits, especially a lot of PC4000 (my GSkill in particular), so you may find you still need a divider to hit your cpu max, especially with low multiplier procs like the 165.

When using dividers, the formula for calculating memory speed is not as simple as cpu clock * ratio, is is in fact cpu speed / ceil (cpu multiplier * (200 / ram divider)) where ceil = ceiling (round up), and ram divider = 166 or 133 etc. There's a tool called A64MemFreq which calculates this for you so you can work out your ram speed before trying a new combination of cpu oc & memory divider.