I bought gtx 780 couple days ago and i opened gpu-z and saw that card is running on pci 2.0 knowing that my motherboard supports 3.0. I found on internet software that force-enable 3.0. I tried it fallowed all instructions. Everything went fine a restarted my pc and since then just blackscreen. No picture nothing. I thought that motherboard bios was wrong so i changed it still nothing. Then i tried nvflash and nvflash does't recognized my card. I dont know what to do