Basically my problem is this: My old 500w PSU by WinPower, which I know aren't the best, struggled to power my GPU (GTX550ti) and eventually my GPU wouldn't display anything so I replaced it with a 520w Antec HCG-520M which was recommended on another post as an ideal PSU for my GPU. I also added an Arctic Cooling Freezer 7 Pro Rev.2 to ensure that everything was keeping relatively cool. Before putting the GPU back in I booted up using the onboard GPU to make sure everything was running, which it was, however when I fitted my GTX550ti, there is nothing showing on screen although all the fans are running and the keyboard and mouse are lighting up which I'm guessing means the system is booting up? The only way I can get a display is to remove the GPU and plug in a VGA cable to the onboard GPU. I'm sure the PSU is enough to power the GPU and I'm also sure that the GPU isn't faulty in any way as it was running okay last week. If theres something I've not covered ask me and I'll try my best to answer however I'm no expert. Any help would be appreciated.
Motherboard: Asus P5G41C-M LX
CPU: Intel Core2 Quad Q8400 @ 2.66Ghz
GPU: Zotac GTX550 ti
RAM: 4GB DDR3
PSU:
Motherboard: Asus P5G41C-M LX
CPU: Intel Core2 Quad Q8400 @ 2.66Ghz
GPU: Zotac GTX550 ti
RAM: 4GB DDR3
PSU: