Black screen no signal input

[bigpopcat]

I am having a problem with games lately and I have spent weeks trying to find out the problem but I just can't figure it out. I will play a game for about 5 min and then my monitor goes black and then 2 seconds later there's a no signal input displayed on it. This is happening in many games like Magicka, Bad Company 2, and even 2d games league of legends. I have played these games before with no problem but all of a sudden it's happening. So here's what I've done:

Updated to the newest graphics drivers and even downgraded to old ones

Checked the temp, nothing over 60c in my gpu and nothing over 30c in my cpu

Re-installed windows 7 (which fixed the problem for a little bit)

No problems in my DxDiag

Considered my card to be broken

Used one monitor instead of 2 which didn't make a difference

I can run the PCMark 11 benchmark with no black screen. I can run many other games like darkness II and Metro 2033 fine with no black screen. But i'm starting to see an increase with my problem in many games, even ones i played before with no problem.

So if anyone can offer any suggestions that would be great!

And here are my system specs:
Ati Radeon HD 5970 2gb
Amd Phenom II 1090t
400gb HDD
1070w PSU
LCD Monitor (Requires a VGA to DVI adapter)
Msi 790X-G45 Motherboard
8gb DDR3 ram

PS: I have figured out that I can play any game without error as long as it play it in windowed mode, but if I enter fullscreen, instant no input.

[YahooElite]

RAM would be my first guess.

Test each RAM stick individually and run Windows Memory Diagnostic. that'll tell you if its a RAM issue or not.

Try reseating your Graphics card, double check all the connections from the Power Supply.

Could even be a failing hard drive, but personally id check the RAM for problems, on my DDR2 system 2 systems ago i had the no signal issue while booting the PC, 1 of the DIMM slots was the problem, it caused issues while the PC was on and working as well if the Case was moved even in the slightest.

[TeKraken]

I used to get this occasionally when using a dvi/vga adapter, but my case wasn't as severe as yours, mine would just be for 10 seconds or so then come back on.

[YahooElite]

Yeah could be that as well

[rotNdude]

It's one of four things, the monitor, the video card, the PSU or the cable port.

[YahooElite]

In my case it was the RAM causing it, but eh..

[bigpopcat]

Anyone know why it only works in windowed mode?

[Bad_Motha]

How old is your monitor?
Could be on it's way out perhaps. Try the display on another machine if u can, as well as trying another display on your troubled system. See which is the real culprit.

[bigpopcat]

Well i tried a different monitor, but nope. Same result. So I take it then it's my graphics card and not my ram?

[Bad_Motha]

It could still be your RAM though.

Remove all RAM from the system, turn it on. It should produce a series of beeps to signal "No installed RAM"

Then try installing just one stick of RAM only and turn on the system. If it fails to boot, power off, remove that stick and try another.

I would also remove the video card and re-seat it back into place. Very possible it's just slightly out of place.

[bigpopcat]

Fixed it! Took apart everything in my computer (PSU, Graphics card, Hard drive, ect) and got some Q-tips and a can of compressed air and I cleaned everything out and put on new thermal paste on my graphics card GPU's and VRAM. I didn't think this would ever work but hey it did.