PSU only powers computer when video card is unplugged

[Lemmiwinkler]

I turned my computer on yesterday and after about 5 minutes of use it abruptly shut off. After checking the wall connection and the back of the power supply i figured that i had a faulty psu. But before i just replaced the psu i did the paper clip test and the fan did spin so i hooked everything back up and tried powering it back up but got no response. I unplugged everything from the psu except the motherboard and it powered up no problem. I then figured out that i could plug everything in except the video card. When i try turning on the computer with the video card plugged in i can hear a noise that sounds like a spark and the fans spin for 2 seconds then nothing.

the reason why i was a bit uneasy about replacing the psu is because i had recently just done the same thing to another older psu on the same computer. The older psu had worked fine until i upgraded to windows 7 and then after a week it went out. so i upgraded my psu from 450 watts to 550 watts thinking that since i had set the power options in windows 7 to high performance i just needed to add a bit more juice. But now i run into a similar problem.

my system specs are
amd dual core
raedon 4850
bfg 550 watt psu
4 gigs of ram

 

[Onus]

Was that one of the older BFG PSUs with a little red voltage switch on it? When you select a new PSU, choose one with full range active PFC (no little voltage switch) and 80+ certification. You can get an Antec Earthwatts or Neo Eco without spending an arm and a leg. A 380W Earthwatts could run your rig, but not leave much headroom; you don't need any more than 500 watts unless you might want to Crossfire, in which case get 650W.

 

[Lemmiwinkler]

my old psu was stock with the case i bought and was pretty terrible. The new bfg psu i bought does have the little red switch on the back.

dont plan on doing crossfire but 380 w seems a bit low.

but i guess the question i meant to ask is that its my psu that is bad and not my video card sitting on a bad slot (only one pcie 16 on my mobo or i would have switched) or something else causing the problem?

 

[Onus]

Those older BFG PSUs are crappy. Yours probably croaked. Being able to power on with minimal load doesn't really give much information.
Just pick up a 500W Antec Earthwatts or Corsair VX-450 and have done with it.