Nvidia Geforce Gtx 645

Hey everyone, I have an alienware x51 Revised 2 and can’t get the display to work correctly using the DVI. I have tried Nvflash (5.163) for restoring Vbios(GK106.rom), but it has made no difference. Current Bios version: plus DVI display works only with 60 hz. Anything higer than 60 would give me a black screen, or a distorted red screen with lines. At the same time, the GTX 645 can display to the display port above 60 hz. Anyone have any suggestions to how I maybe able to get my 120 hz working with this problem?