p4c800 and 400mhz ram freq

I have one OCZ 3200 and 3500 rams
shouldn't they be able to run at 400mhz freq?
everything set at default, I change the speed to 400 and computer doesn't boot or lock up at bios.

what's up?

now this is odd...
I can O/C to 240mhz FSB with ram speed at 266mhz
but once I change to 400mhz computer doesn't boot.
and with no O/C i can change to 400mhz and computer now boots fine...
i dont know why my rams wont run at ddr 400 after overclock

What processor you running on?
fsb 240mhz is too high for DDR400 on pc3200 and pc3500. Switch to DDR333 (320mhz). You should be able to get at least fsb 250mhz if you're running a p2.6 or 2.4

Prok you just told him to get slower RAM... did I not read that right?

Check your timings, make sure they not too aggressive. If needed give those sticks some more juice. 2.8-2.9 is good.

He means change the CPU:Mem ratio.

Yes, Amino got me on that one - change the cpu:mem ratio. At a 1:1 ratio I've never been able to set the fsb much higher than 215mhz - I'm running on pc3200. I can't imagine that pc3500 would allow for as high as 240mhz so switch the ratio to DDR333 in the bios, then bring up the fsb until the ram is maxed out.

While we're on the subject, I'm still new to oc'ing and I haven't really played with the ram timings too much. When I think I'm at my max oc I've made the ram timings both as relaxed and aggressive as possible - setting them more aggressive definitely didn't help, more relaxed didn't allow for a higher oc. Is there anything else I could do with the timings to produce a higher oc?

Better to relax them a little if you're OCing RAM. It may give you a couple more mhz, but as far as I see it just saves your RAM.

i have a p4c800 board with a 2.4 c and my ram is 2 sticks of micron ddr512mb 400mhz pc3200 and i managed to raise the fsb to 255mhz and i am running it in dual channel mode

You probably have the DDR setting at auto or 320mhz.