About to be very Angry. No Signal to display.

Hey Guys,
So I recently bought a new stock asus computer. I figured i would change a few things in it so I bought a new power supply (Corsair GS800) and a new graphics card (First AMD XFX R7770 now the GTX 650).

I set up everything perfectly and it worked for a little bit, but then it hit the fan. Every so often I would get no signal to my monitor while using a HDMI cable. It would work every now and then and when it did work it was awesome. I returned the graphics card and got the 650. The same thing, no signal. I'm at wits end trying to figure this out. No Signal with both cards, the stock card and my HDMI straight to the computer.

I'm a little irritated right now so I may have not given much information. If you need more let me know and I will provide as much as I can.

Thanks.