Well, a good way to check is to test with another display - Your ADC Video card will also have either a DVI or VGA Port on it.. if the video is bad on that too.. then you have a bad video card..
The Power supply is not in play - The Display gets its power from the video card, and the video card gets its power from the logic board, and the logic board gets it from the Power Supply.
Basically if it were the power supply's fault - the computer wouldn't turn on.. and display would be your last problem.
You could always Hook up a DVI Monitor to your ADC port with [http://www.amazon.com/gp/product/B000067RLH?ie=UTF8&tag=mattfreycons-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=B000067RLH|One of These]