I was looking on newegg for your mobo and saw what looked like a VGA port (it was a lo-res thumbnail). Turns out it was a serial port.
Best Buy seems to have removed the PSU tester from their inventory. This is a pretty recent change as I got one from them not three or four months ago.
If you've tried all of those steps and the graphics card has a green light on it, it's hard to tell. It could be the mobo or graphics card unfortunately.