My old 8800gt is starting to go bad and I need a suggestion on replacement. I tried to take my 660 gtx but I can't even get it to bios. Something cheap that would be the same or better than the old 8800gt would be preferred. Something that is actually compatible would be helpful.
Antec NeoPower 650 Blue 650W ATX12V / EPS12V SLI Certified CrossFire Ready Modular Active PFC Power Supply
Unfortunately no one can guarantee you compatibility with machine that is 5+ years old. Buy from sites that you know you can return easily.
Budget offers: 750, 750TI. Very new, affordable, a bit slower than 660, but definitely better than 8800, initial reviews are full of praise...
630 DDR3 is slower than your 8800. For performance comparison check: http://www.tomshardware.com/reviews/gaming-graphics-car...
750 and 750 TI are not added yet as were released last week, but I estimate they 750 will be in the same layer as 560, 560 TI (or one above that).
There are several 750s ~$120 on amazon and newegg.
Do a BIOS update on the motherboard and try that 660 again, no real reason why a 660 wold not boot on that motherboard and power supply, although there is a small chance of it. Make sure you have all the power connectors in.