Hi Guys, This is driving me crazy. I bought an HP PC last year which I have upgraded a few parts in, current configuration is: Motherboard: Intel H61 Chipset (std) Power Supply: Corsair GS600 Watt (upgraded) Ram: 8 GB (std) Processor: i3-2120 (std) Graphic card: HD 7770 (Upgraded) Now everything was running fine with the 7770, but I decided I needed a bit more FPS, so I bought a Gigabyte 7870 OC. Took out the 7770, plugged in the new card. Both PCI-E cables etc. (everything 100%, it's fitted correctly, the monitor is plugged in etc. So please don't ask about this stuff). but when I boot the PC all I get is a black screen. Strange. I plugged back the 7770 and everything worked as it should. Tried again with the 7870.. Black screen.. I thought, ok card must be DOA, so I ordered a second card, this time a Club3d Joker XT 7870. Same exact thing.. Just a black screen. The PC turns on, all fans are running, but monitor shows no display.. When I plug back the 7770, everything works again.. This puzzles my mind. What the h*** is wrong here?