Good news folks, I pulled out my old Crosshair III Formula, swapped the 955BE (overclocked to 3.9 again) out of my apparently dead A770DE+, popped my cards in with an 800w Mushkin PSU and 8GB DDR3, and upgraded to Win7 x64 (used XP on this machine before), so I'm taking it to work tomorrow and firing it back up to crunch and fold. The only downside now is that I can only allocate 40% of my CPU (with 100% thread time) to crunching while folding on 2 ATI cards. On XP I was able to pull off 60% without maxing out more than one core. Increasing to 50% causes my CPU to go from 80% to 100% now.
The back of my A770DE+ under the MOSFETS was discolored brown, the solder resin on the MOSFETS turned brown, and the power supply's P4 +12v leads had "folder's burn" as well as some discoloration in the board's P8 socket as well. I can only guess I pushed the board to its limits over the last few months and it finally blew up.
Luckily, my CIIIF has 8+2 phase delivery so I doubt it will be blowing up, although it has developed a strange problem where CMOS gets wiped when the board is unplugged for a while. Changed the battery twice, no dice. It's 2.5 years old, I guess it's getting a bit tired.