New Graphics card slowing down computer


Jan 10, 2013
I have installed a Sapphire HD 7750 1GB GDDR edition into my acer predator g5900. The desktop etc looks clear but when i try to run any game they are completely unplayable with sub30 FPS. All the card requires is a 400W power supply and i am running on 500w. I have all the drivers installed and updated and all of the old drivers removed.

What is strange is after leaving my computer for a couple of hours i came back to give it one last try, and black ops 2 ran on ultra 1650 x 1050 with 85 + FPS. This didn't last for very long though.

If anybody has any idea on what this could be please let me know

Some specs for my computer:

Hard Drive 500GB
CPU family Intel Core i5
CPU nominal frequency 3.20GHz
Operating system: windows 7
PSU 500w