I have an Asus Striker II Formula motherboard with an Intel Core 2 Quad 6600 CPU and 4GB (4x1Gb sticks) of Corsair PC8500 DDR2 Dominator ram running on Vista Ultimate 64bit. I thought this system would have no trouble at all overclocking especially since I'm watercooling but no, I can only seem to get my cpu up to about 3GHz before it fails to boot. Even when I run it at 3GHz I sometimes get a "Hardware Melfunction Error" screen when running games so I since put it back to its defult values. Any idea why this is happening? I checked my temperatures and everything seems OK, I've raised and lowered the voltages but I still get the error. Any help would be appreciated.

With my Asus P5N-e SLI I had the same experience. Some boards have FSB holes were no matter what you do it wont boot at a set group of FSB settings. Try dropping the multiplier and finding what FSB settings it will boot to. Just because it wont boot at 450 doesn't mean it wont boot at 485. Also try moving the northbridge voltage up and make sure the northbridge is cool. mound a fan on it. One bad thing with watercooling is that the northbridge no longer gets that wind off the cpu cooler.

Thanks for the tips. I have some case fans that blow on the northbridge and memory already but maybe I'll look into actually mounting one, maybe thats the cause of the hardware melfunction error?

let us know how it goes

Id say monitor the NB temp, and try chagein the FSB around. Are you running the ram in 1:1 with the FSB?