But how do you know its a hardware problem?
There was no power to mouse or keyboard and no display when 7850 was in. i tried 1 stick of RAM, resetting CMOS, rewiring system but still the problem persisted. I then took the graphics card out and tried it. Everything worked fine except i didn't have the right VGA cable for onboard graphics. I then got another graphics card from an old pc and am now using that instead and everything is fine. I might try putting the 7850 in again though.