New Build, Screen Goes Black After ~:30

Ok, I know there have been lots of questions like this already... so I am sorry to start a new thread, but I have read through most of them and tried the solutions and nothing seems to help... Feel free to link or move me as necessary.

I just built a new rig:

Mobo: Gigabyte 990fxa-ud3
CPU: AMD Phenom 2 X4 965 "Black" 3.4 Ghz
GPU: MSI Radeon HD 7770 (http://www.newegg.com/Product/Product.aspx?Item=N82E168...) linked because there are a few of these...
Ram: G.Skill Value 8GB
HD: Western Digital Blue 1TB 7200 RPM

Ok, so I installed Gigabyte and MSI's driver packages from the CD's. Right after I got through installing Afterburner (this may/may not just be coincidence, not causal), my screen started going black after about 30secs after going to the desktop (Win8 64bit).

I was able to get into Afterburner long enough to turn the core clock down to 985 and the mem down to 1075 (comes stock @ 1000/1125). The screen is fine when I am messing with afterburner, but :30 after I go back to desktop, the screen goes black. The monitor stays on, no lights change... it is still receiving a constant video signal, its just a black signal.

I am pretty much a total noob, but it seems to me that if nothing changes but the video signal, this is a GPU issue. I am not sure what to do form here. Any ideas?

Edit: I adjusted the core-clock down, because I was worried it was a voltage issue. But that didn't solve it anyway, and I was probably digging in the wrong area.