When I turn my PC on I can hear the HDD, fans etc all start up, the hard drive light comes on etc but the monitor says "no signal". The reset button doesn't work so I turn it off and when I turn it on again it works perfectly. No error messages or anything. This happened when I upgraded the firmware for my mobo and upgraded to Windows 7 SP1.
So far I've tried formatting my PC, setting my PCIE graphics card to be booted up in BIOS (as opposed to the on board one), trying a different input in the graphics card, checked the power cables are all plugged in properly, upgrading all drivers to everything my PC has, upgraded the firmware on the mobo.
mobo: Asus Maximus V Gene
GPU: Nvidia 2GB EVGA GTX 670
PSU: 850W XFX XXX P1-850B-UKB9
CPU: Intel core i7 Ivy bridge
Ram: 8GB (2x4GB) Corsair DDR3 Vengeance