I have been having a problem with getting my computer to start up to windows for a few weeks now. I have been trying to fix it myself. I reinstalled windows, didn't work. I got a new hard drive, didn't work. I got a new motherboard and ram, didn't work. I got a new cpu, didn't work. My computer has 850 Watt power supply, one cd-rom drive, evga 8800 gt video card that's 3.5 years old, 3.9 Ghz new AMD cpu, gigabyte motherboard. The computer powers on, but nothing appears on the screen. The computer makes a loud, long constant beep when you press the power switch on the computer case. The beep won't stop and computer won't power off when you press the power switch in like it normally should do. The heat sink fan kind of stops and starts when computer is on, so it makes me think the power supply isn't supplying enough power? I took it to staples for repair, but they said they couldn't extensively look at it since it's a custom built computer. But, they tested the power supply and they said it was fine. I contacted the gigabyte motherboard company and they said to send it in for RMA and new motherboard. I don't want to do that and wait on it to come back.

My main question is, does anyone think I need a new power supply that's 1000 watts or more to supply these components? I had to do that when I got a new video card or some other part a few years ago. Any other ideas? Would bad case or video card cause this? I don't think it's video card because my old computer setup let me at least go to safe mode in windows and I could see things on the screen. Thanks for your help.