I have this exact same issue; and it is not because of using a TV as a monitor or a bad DVI cable.
I will admit to using a DVI cable; but have tried several, as well as a VGA connection using a DVI/VGA converter. I unfortunately do not have Displayport on my monitor.
When the machine boots, it will loose its picture - either immediately after windows log-on, or after quitting a game. Once the picture has gone, there is no way of getting it back short of shutting power completely of (on the wall), removing the graphics card, booting once (sometimes twice) to fore the motherboard to reset its resource allocation to PCIe ports, and then re-insert the graphics card.
The problem is new, the machine used to be stable before a minor overhaul this weekend. I did three changes:
1.) Upgrade RAM to a slightly faster kit (same memory amount)
2.) Update BIOS to latest, to attempt an overclock of the 3820 CPU
3.) Replaced the air-cooled ATI 6870x2 graphics card with a watercooled GTX 760.
After experiencing the issues - primarily seeing the PC boot the OS - I naturally tried reverting the changes to isolate the problem. It was extremely disappointing to realize that nothing seemed to solve the issue.
So it isn't the RAM, and it isn't the graphics card. I tried downgrading the BIOS to no avail, but the old version I had before is not available for download so I can't downgrade to that exact version.
The motherboard has not previously been overclocked, and the only attempted overclock we tried with was the AI Suite's automatic "Level up" function. So presumably settings were within acceptable limits; still, reverting everything to default settings did nothing to fix the issue.
The motherboard and CPU are both watercooled - with temps never exceeding 50 C. It runs about 3 degrees above ambient temp when idle (including the GTX 760 on the loop) and about 50 C when running BOINC on all cores and the GPU. I think that's pretty acceptable and that cooling isn't the problem. I have run countless PC's on water for well over a decade so I am also quite confident I din't make any errors. It is also worth noting that the MB and CPU has been running on water for about 2 years with no issues, with very low temps (it was watercooled for noise reduction, not overclocking).
Any input or suggested actions to further diagnose the issue would be appreciated.
I note that a lot of users report variants of this problem on the 'net, so googling "rampage IV extreme no POST" or "rampage IV extreme no video" seems to indicate there is a wider issue in play here. Sadly I have been unable to identify a working solution.
Re-purposed DELL XPS 730 H2C casing | Rampage IV Extreme | i7 3960x | 4x8 GB 2133 Mhz Corsair | Dual Powercolor 6870x2 (4 GPU's) | Dual Intel 520 SSD 240 GB in Raid 0 (System) | Dual WD 1002 Caviar Black in Raid 0 (Storage) | Re-purposed DELL H2C cooling unit with EK cooling blocks | Specs currently altered for stability/testing | +4 other rigs in the household