Well, i have the PSU in the comp right now, and have my old GPU in as well, and it's running fine. As a side note, one of my buddies decided to try something on it, and he took the card out of the comp, set it on an anti-static bag, and plugged in the 6-pin connector, and got the same results as when i had it in the comp. The problem only ever occurs when i have the 6-pin connector plugged into the card. When the card is in the PCIE slot, the computer boots, but i have to use the onboard graphics.