Computer comes on but not monitor I have a Dell XPS600 geforce 7900gtx sb xifi left computer on lastnight went to bed, got up this morning computer was off. Bit power button to come on the button just clicks starts to come on then goes off. After clicking button a while it finally comes on. Fans power up cd drvies power up sounds like everything is running but the screen will not come on, it stays black. I have taken out video card an sound card cleaned an reseated. Checked all cables inside all is pluged an seated properly. So the short of it is computer shutoff itself an now when comes on monitor will not power up but fans an drvies do. any suggestion with this would be appreciated, since im starting to thing my mobo as died.