Hi,

I have just installed a GeForce 6600, 256 Mb (AGP) as well, and am getting this same problem, only I have the internal power supply connected. I played Battlefield2 for about 10 minutes and the graphics crackled and the system froze. On reboot all the data displayed on the initialization screen was distorted. I turned off the system, and the next morning (after cooling down) it was good again. I haven't tried gaming on it yet though. I strongly assume an overheating issue and so have others. I might need a new power suppply (2 years old) and may need better cooling in my system. I will also try to underclock the GPU as well. I will keep you updated, but until then, any more suggestions?

Also, since the addition of the hardware (more directly the power supply addition) I have lost all sound. It's onboard and I've checked the whole system out (including BIOS Audio option to ensure it's enabled).

Cheers.