Well, I am almost there. I got my new cooler installed (thanks to NewEgg for stepping up and paying for the return shipping) and began incrementing the multiplier and voltage. I got 3.8GHz stable (400MHz 9.5X) but couldn't hit the magic 4GHz with a 10X multiplier. First shot it gave me a BSOD at boot. I bumped the voltage a little and got it to boot, but it gave a BSOD after a few minutes. Bumped the voltage a little more and got it to seem stable. Then I ran Prime, but it quit after about 15 minutes. One more bump to the voltage and got Prime to run for over 2 hours with both CPUs between 45-55C (according to CoreTemp). But alas, when I woke up this morning, it had crashed with a BSOD. The CPU voltage under load as reported by CPU-Z was 1.424V.
So my questions: should I bump the voltage a little more and go for the gold at a 400MHz 10X multiplier? Or try to get 500MHz at 8X stable? If it is the latter, I couldn't get it to even boot - so something was funky with either my voltage setting, memory timings, or both. If I try 500MHz, how do I set the memory timing (DDR2 PC6400)?