After a buying a new gtx 660 gpu for my HP pavilion and a LOT of troubleshooting I brought a new motherboard (Asrock H71M-DGS) to get my pc to work with the card. After installed the new board, I found that the pc will only boot with one stick of ram installed into the motherboard. With 2 the screen is given no signal, plugged into the gpu or the motherboard. The pc boots fine without the card in and 2 sticks of ram installed.
The card also works fine in my friends system, and his card (GT 630) as well as my old card (HD 7450) both work fine. I have a sufficient power supply (Corsair CX600M) and have connected the power cables, as well as seating the card correctly.
As I said the computer will only boot with one stick of ram, and everything is completely normal once this happens, only thing is I only have 2GB of ram rather than 4.
Any help would be appreciated, I have spent weeks trying to get this card to work.