So I'm currently using a multiplier of 9 with a fsb of 355 (which is 3.2ghz). But when I lower the multiplier to 8 and raise the fsb to 400(also a speed of 3.2ghz) my PC refuses to boot. I dont think I need to raise the Vcore because it's the same clock speed. What can cause this? Thanks.
My old system had that exact motherboard. I used to have a Core 2 Duo 2.53Ghz CPU in there.
Anyways, I believe it might be your North bridge for your motherboard (if you look at it, there's a passive copper heat sink on it) is overheating.
Back in the day I was able to OC my CPU to about ~3Ghz, but it seems like the P5W DH Deluxe was not a very good overclocker (maybe I didn't have a gold sample CPU, maybe it was just my motherboard).
What memory divider are you using? When you overclock the FSB, it overclocks everything else, including memory. Also, some of the older intel boards had a FSB strap around 400. My old P965 was unstable at 400, but stable at 401 because of this. Read a bit about it here:
Generally, Core2 systems overclock better at their max multiplier. Memory runs a little slower, giving you somewhat better memory stability at the lower FSB freq. And because, for the same core speed, performance does not scale linearly with FSB freq. In fact, you will gain very little extra performance at 400 X 8.
Next, all CPU's are a little different. I had a Q6600 that would run all day at 3.6 GHz (24 hour P95 test).
Check the strapping. And make sure you are running at 1:1.