Overclocking motherboard fsb overclock limited by cpu?

Does it make sense that the achievable fsb on my motherboard is limited by the cpu that I have installed?

I have an ASUS P5E3 deluxe motherboard which according to reviews I've seen will surpass 450fsb without an issue but I cannot reach 400, the maximum that I can post at is 395. This is with the cpu multiplier dropped to 6x (I've also tried with 7x and 8x) and the RAM divider lowered (also tried with 2N CR and relaxed timings).

I'm guessing that because my E2160 is intended to run on an 800mhz fsb taking the system to 1600fsb is a problem not because of my motherboard's ability or because of the sheer clock speed of the cpu (after all 400*6=2400 and I can run stable on this cpu @ 3300) but because of the fsb of the cpu.

What do you all think? Am I on the right track or is fsb just simply a matter of motherboard and northbridge voltage?

 

did you remember to lower the FSB: DRAM ratio?

400 for a P35 is a bit low to be an limit, and it should be achievable for all the newer CPU's.

but at 500 FPB, it is very possible that CPU will stop the FSB overclock. eg, my Abit iP35 Pro is known to be able to do 500FSB, but i can only get to 450FSB because of my RAM and my CPU

 

yes, certain CPU types are known to have low fsb "walls".

 

what are all of the other settings you have in the bios?
and what happens when you try to start the pc? no post, just a black screen, bsod in windows, etc.

are you upping the voltage for your northbridge/southbridge to handle the higher fsb? how about the pci speed? is it locked at 100? leaving that on auto can kill cards that are plugged in.
Basically when going for the highest fsb on a system you should not leave anything on auto.

and watch the heat on your northbridge and southbridge, as you up the fsb and the voltage for them they will start to overheat.

 

It's an X38 not a P35. Yes I have lowered the ratio.

That's what I think too, it's just that the CPU cannot run at the fsb required not the motherboard.

Posts and stable @ 395, no-post at all at 400.
PCIe set to 100, I certainly wouldn't be able to go from 200 to 395 if the pcie bus was tied in!
Northbridge voltage is raised to 1.55v in the bios and temp is great. Southbridge is surely irrelevant to the fsb and doesn't heat up much anyway.

Basically, I just need to lay my hands on a 1066 or 1333 fsb CPU now to see! Can my curiosity be enough of a justification to splash out on one?

 

not sure if its still an issue with the newest chipsets but the older ones had a small black hole between like 396 and 404 that they won't clock to because of a ratio limit. Maybe try setting your FSB to 406 and see if that works?