Computer won't boot up since I put in new graphics card

path134

Reputable
Jul 9, 2014
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Hi my build is as follows:
MB: GA-Z77-D3H
CPU: Intel i5 3570K (overclocked from 3.4 to 4.2 GHz)
RAM: Kingston HyperX T1 8GB
PSU: OCZ750FTY
I recently upgraded my XFX HD 7750 Double D Black Edition to an XFX R9 280x Double D Black Edition and now my pc won't boot up. All the fans turn on and I can hear the HDD working but the screen remains black. When I remove power to the card, the pc runs as normal. The PSU delivers 750W ((minimum for the GPU) so I am unsure why there is a problem.

Side note: I also installed a new HDD as secondary storage and that isn't being recognised.