Problem with new GTX 660

Hardware Hub GPU
1

   Yesterday I got my GTX 660 and it was running like a dream, playing all my games at max settings, couldn't be happier. However, this morning I noticed some crazy framerate drops whilst playing CS:GO, and I then checked it wasn't just a source thing, but I got a similar result in other games like SSF4.
   Now, ever since I restarted my computer, it doesn't recognise a GPU is plugged in and has reverted back to my integrated Intel HD. Could there be an issue with the GPU or am I missing something obvious?

Thanks

EDIT: My specs: Gigabyte z77-3dh MoBo, 3750k i5 processor, 8gb 1600 Kingston HyperX Ram, Seagate 500GB hard drive

2

Driver version, what are you using.

3

Ah no don't worry man, it turns out it was my crappy case being the problem, the screw hole for the card wasn't aligned and was forcing the card in at a funny angle and I didn't even realise, everything is fine now and running better than before, just need to consider a new case xD Thanks