CPU: AMD Phenom II X4 940 Black Edition
MB: ASUS M4A78-E DDR2 Motherboard
RAM: Corsair XMS2 DHX TWIN2X4096-6400C5DHX 4GB DDR2 2X2GB PC2-6400 DDR2-800
PS: OCZ ModXStream Pro 700W Modular Power Supply
CASE: Antec Three Hundred
OS: Windows 7 Professional 64
My first guess is that you have a possible PSU issue with the GPU that you installed.
* Did you only use the onboard GPU until you installed the 6770? If so than it could be the PSU, but is possibly the GPU, not 100% sure. Your PSU shouldn't have any issue powering the 6770, but it's something to check out if you have a spare PSU available.
Thanks for the reply. Is OCZ known to overrate their power supplies? I got the impression a 700W, even if overrated, should be ok. Unfortunately, I don't have a spare to swap in. The latest BSOD points to dxgkrnl. Any suggestions?