PC not booting up when I installed a new gpu

vowtaker

Honorable
Sep 30, 2013
7
0
10,510
So I bought a new graphics card to replace my old one, it's the Powercolor HD7850, put it in the mobo but when I tried to turn the pc on, it doesn't boot up.
All the pc does is make the fans spin including the processor's heatsink and the gpu's fan.
I switched back to my old HD4850 and it doesn't have any problems booting up. Can you guys help determining the problem?

My PC specs are:

Processor: Intel i5 3570
Ram: 4gb ddr3 1333
Mobo: Intel DH61WW
PSU: Cougar ST 500
Current GPU: Powercolor HD4850