I'm really jeolous of some people's easy overclocks!  After 3.8 ghz, It seems the voltage requirements go up exponentially on my particular chip.  I have an Asus p6t (not the deluxe).  I'm currently running at 3.93 ghz which requires at least 1.375 volts.  I'm very very hesitant to push it further, but I feel I need just a little more speed.   Temperature isn't a problem, but how far can I safely go with the volts?

Wow, I tried those settings and my system didn't even POST at those voltages.  I think the reason for the massive discrepancies is that I have a C0 stepping i940, whearas all the cool kids must have a D0 stepping.  I switched to the 21x multiplier and a 189 base clock, which requires 1.4v;  It won't pass Linpack testing above that speed no matter what voltage is applied (It doesn't give me the bsod, but instead just tells me I failed the tests).  So 3.97 is as high as it will go for me, and I probably ought to back it off from there.  Darn!

I should have posted that:  My uncore is 1.35..My cpupll is 1.86 with the 3.97 overclock.  I agree that 3.97 is good, but I'm running very high detail settings with a 4320x900 resolution (somewhat wider fov than the pic in my sig), and I find that my frame rates with some of the heavier add ons is rather dismal even after performance optimizing.  I also have 2xgtx285, slightly overclocked, with a slight fps improvement using SLI, so that probably isn't a bottleneck. Despite my fears of burning up the processor, I will test it out to see if the 3.97 with 1512mhz memory speed is better than the 3.93g w/1656 dram frequency that I was previously running at.  Like you said, I kind of doubt that I will see any difference and the 1.4v cpu makes me wake up at night craving icewater.  Also, you have the Deluxe motherboard and I don't, so I wonder if that could account for it.  Otherwise, my chip just might be a bit of a runt!