Black Screen With New Graphic Card? 7870

[FONT=Verdana]Hi Guys,[/FONT]
[FONT=Verdana]This is driving me crazy.[/FONT]
[FONT=Verdana]I bought an HP PC last year which I have upgraded a few parts in, current configuration is:[/FONT]
[FONT=Verdana]Motherboard: [/FONT]Intel[FONT=Verdana] H61 Chipset (std)[/FONT]
[FONT=Verdana]Power Supply: Corsair GS600 Watt (upgraded)[/FONT]
[FONT=Verdana]Ram: 8 GB (std)[/FONT]
[FONT=Verdana]Processor: i3-2120 (std)[/FONT]
[FONT=Verdana]Graphic card: HD 7770 (Upgraded)[/FONT]
[FONT=Verdana]Now everything was running fine with the 7770, but I decided I needed a bit more FPS, so I bought a Gigabyte 7870 OC.[/FONT]
[FONT=Verdana]Took out the 7770, plugged in the new card. Both[/FONT] PCI[FONT=Verdana]-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.[/FONT]
[FONT=Verdana]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.[/FONT]
[FONT=Verdana]Same exact thing.. Just a black screen. The PC turns on, all fans are running, but [/FONT]monitor shows [FONT=Verdana]no display.. When I plug back the 7770, everything works again..[/FONT]
[FONT=Verdana]This puzzles my mind. What the h*** is wrong here?[/FONT]
 
Evidently the HD 7770's driver is not compatible with either the 7870 OC or the Club3d Joker XT 7870. Try installing the 7870 driver before installing the video card
 
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