I re-seated my CPU fan/heatsink today. As I suspected, the thermal grease application wasn't complete across the entire contact patch. I cleaned it all off then put a couple of drops of arctic silver on the heatsink contact, then I spread it with a plastic putty knife, making sure it was totally covered with a very thin layer. I was glad that I didn't have to remove the mobo to re-seat it.
So I fired it up and ran a short, ten string (1 string for each core 5 times) Prime95 test at 100% load on both cores. Temps at stock settings never exceeded 55C. The test ran 7 minutes.
Then I rebooted to BIOS and set my FSB up to 1600 for a 3.2 Ghz clock and ran Prime95 again. After five string sets, temps had climbed to 68C and 70C. The test lasted 6 minutes but the temps were more than I was comfortable with, so I went back into the BIOS and noticed that the auto voltages had re-set CPU Core from 1.2xx to 1.4 volts. I had documentation from others that at 3.2 Ghz I should be able to get by with 1.3-1.35 volts, so I set it down to 1.3.
The system wouldn't boot. So I tried 1.325 and booted. 2 strings into Prime95 I suffered a fatal crash and had to hard boot.
Entering BIOS again, I noticed that the low end of the "green zone" on my CPU Core was 1.375 volts so I set it there, re-booted and ran Prime again. 5 string sets, 6 minutes, no problems and temps stable at 62C (ambient room temp 74F).
I'm reasonably happy with that. I've got a 12-13% gain in speed from the CPU and I can't really think of a real-world application that's going to run my CPU cores at 100% steady. Idle temps are still in the low to mid 30's and normal operating temps are still under 50C. Although I've heard of people getting close to 4 Ghz at this voltage setting, I don't really want to tr to clock that high as I'm already linked and synced to my RAM (DDR2 800) at it's performance settings (4-4-4-12 at 2.0 V).
I might play with the voltages again tonight and see if I can get them down at all and remain stable. If I can I'm sure my temps will drop a little more.
Just thought I'd share.