No display after exiting game or ALT+TAB gtx650

I installed a gtx 650 and antec vp-450 in my Girlfriend's prebuilt today. This is the computer in question: http://us.gateway.com/gw/en/US/content/model/DT.GDDAA.016

After installing the card, the computer recognized it right away and the WEI saw it and changed graphics and gaming graphics from 4.8 to 7.2. I thought that was interesting and went to download the drivers and install them. During the installation, the display would turn off and you would have to restart the computer manually. Nothing would wake up the display. I figured forget it and whatever.

She was playing dishonored for about an hour and when she exited the game, it did the same thing. No display at all. The monitor sleeps itself. Again the only way to fix it is to manually restart the computer with the power button.

Anyone have nay ideas? Thanks!