hi there, after installing a new XFX HD 7770 1gb DD my computer when turned on let off a loud beeping sound about 3 times and the light on the front of the case turned red. now my pc won't turn on at all but the light of the case turns green when i push the power button and the light goes off as soon as i let go, i have tried running the pc with no 'extra' components namely my HDD, and graphics cards disk drive and i also ran it with only one stick of ram but still no luck could anyone help me out here.