2008 Mac Pro. Will boot and chime and all but just displays a grey screen on a 30" acd. Intermittently will boot to an apple loading screen with vertical grey stripes. Screen checked with second computer. Able to log in from mba and all files and drives work so I am thinking it's the Apple OEM 4870 video card. Have cleaned it out, tried to boot with bare minimum, reset Pram. No improvement. Sounds to me like a dead video card, but would like any other tips/hints. Thanks in advance.