I recently bought a new Powercolor R9 270x Devil, however when I first plugged it it the Pc would turn on (fans spin, PSU is on) however it wont boot into bios or anything. I turned it back off, unplugged one of the 6-pin power connectors (out of 2) and it turned on but I had to use onboard graphics. I figured it may be the PSU since I had a 550 watt and the minimum requirment is a 500 watt. Since then I bought a new 730 watt PSU, tried again with the exact same results. the Pc doesn't turn on unless the GPU isn't getting power. I don't have another computer to test the GPU on so I'm not sure if that's the problem or what. I also tried an MSI 7770 that only has one 6 pin connector and it worked just fine.
System Specs:
PSU: Raidmax Hybrid 730W
CPU: AMD FX-4100 Quad Core 3.6ghz
Mobo: Unknown, the computer was pre-built.
HDD: WD 1TB Caviar Green
SSD: OCZ Agility 3 128gb
GPU: PowerColor R9 270x Devil
System Specs:
PSU: Raidmax Hybrid 730W
CPU: AMD FX-4100 Quad Core 3.6ghz
Mobo: Unknown, the computer was pre-built.
HDD: WD 1TB Caviar Green
SSD: OCZ Agility 3 128gb
GPU: PowerColor R9 270x Devil