I bought a refurbished MSI GTX 470 and I put it in the top PCIe x16 slot. It was working until I installed the drivers. I kept getting a message that the display drivers have stopped working. I opened up firefox and the whole computer would shut off. So I uninstalled the drivers completely, and tried other ones. It kept doing the same thing, eventually until the monitor would lose signal right before windows booted. Then I bought a new power supply and the problem remained. So I was getting ready to send the thing back for a refund until I decided to try it in the PCIe x8 slot. Sure enough it worked in that slot. Could it be possible that my PCIe x16 slot is broke? Even though the 7800GTX I have works fine in it which makes me even more confused!