I just received my eVGA 8800 GTS 640MB card today. Happy as a clam, I popped that bad boy in my system, and the computer didn't boot. I've had this issue with my mobo before, where with new hardware it sometimes takes a couple resets before it finally recognizes it. Well, after 10-12 resets, I only got into windows once, and even then it didn't recognize my second HD.
Most of the time BIOS just sits there trying to detect my hard drives. After a while, it will sometimes detect both, then report an error with my second (non-boot) drive.
Somehow during this procedure I broke the little plastic tab on the SATA jack of drive #2. Fortunately I fixed it with some superglue after almost having a heartattack (all of my son's baby pictures are on that drive).
I pulled out the 8800, and put in my old 7600GT, and the comp booted instantly.
What's wrong here? Do I have a power supply issue? I have a 550W Rosewill PSU, I thought this would be enough.
I read the specs for your PSU and although i have never heard of it, it seems pretty ok, and it should be able to handle your system. It may be that you have connected too many devices on the rail that shares the 8800. Try rearranging the rails to evenly distribute power among your components. Then again, it may be a faulty PSU. Try sitting your card properly as it is heavy and tends to bend downwards due to gravity. Good luck