My systemspecs:
775Dual-VSTA, C2D E6300, 2x512MB PC400 or 2x512MB PC533, Radeon 9700, SoundBlaster Live!, BIOS 1.8
My computer crashes while playing games, doesn't matter DDR or DDR2.
I've also tried with a Radeon9600. The computer doesn't crash but gives image corruption.
Most of the time, the problems start after running the computer for 24 hours.
After searching a couple days, i've found the solution:
Disable 'AGP WRITES' in Control Center.
AGP can stay on 8x and 'AGP READS' have to stay enabled for performance reasons.
Current settings:
Everything on stock, 1T, PC400, PCI delay trans 1, latency 32
Via 4in1 5.10 - Catalyst 6.8
Some note about the Via 4in1:
If you install the package, most of the time it doesn't install the AGP driver and leaves it to the standard MS driver. For performance reasons you should install AGP manually.
I've also seen many people having problems with PCI-E cards (image corruption) which can be solved by disabling in the bios 'PCI-E Downstream'.