The NO SIGNAL issue

So this issue arose out of no where like some, couple months ago but I haven't been super active on my PC until lately. I bought far cry 3 and with this game and other games I keep getting a "No Signal" to my monitor at random times, whether it's after loading, at the the menu, at certain points of the game(s), or anything.

The only time I don't get it is if I run the games by 800 x 600, then it's fine, but on my native resolution, this problem happens a lot. I can't play comfortably (or at all sometimes) and I tried so many things already. I increased my fan speeds around the case, double checked if all wires were secure and in (they were), increased GPU fan speed, uninstalled/re-installed to latest video drivers, and looked this up all over google without definitive solutions.

I have a ATI Radeon 6970, AMD Phenom X4 9950 @ 2.61 Ghz, 750 watt power supply, Western Digital hard drive, 4 GB of RAM

Games that have the no signal issue so far are Far Cry 3 and prototype 2. There are a few others I can't remember and this issue also happens randomly when just using the PC normally. I can't figure out if it's my GPU that's the issue, the power supply, or RAM or even OS. When the no signal problem occurs, my screen goes blank with "no signal" on it, the keyboard turns off (the lights go off and ctrl+alt+delete won't work), but the PC and the fans are still running. On a note, when I increased my GPU fan speed from 25% to 100% to see if it fixed the problem, when the "no signal" came back again, I noticed the GPU fan speed suddenly slowed down once the screen went blank. I don't know if that'll help but, who knows. The only way I can get out of this "no signal" issue is if I hard restart my PC, and windows will say it didn't shut down successfully. There are no beeps when this issue occurs.

If you guys want a video to see my issue, I will seriously do one so you guys can understand and maybe help, I REALLY want to find the solution to this problem so I can go on and play Far Cry 3 (and Prototype 2, I haven't beaten that yet).

Thanks guys.