PC and display are fine, but they don't work together.

Xeon Rampage

Honorable
Feb 8, 2014
8
0
10,510
Hello everyone,
This one's confusing so bear with me,
About a year ago, I started having a problem with my PC, it would do the following: it wouldn't show any display output, yet the PC was running and the fans were turning. I tried switching HDMI cables with like 5 or more cables, same problem. I also tried using a VGA cable, didn't work.
So I went on and tried my PC with my Television screen using an HDMI cable, it worked perfectly. Like any person with a little logic, I assumed that the problem is with my monitor, but I wanted to make sure, so I tried my monitor with another PC, and it also worked perfectly. So then: I had a PC that works well, and a monitor that works well, but not together.
I took a shortcut and bought another monitor last August. It worked fine for like two months, but then the same exact problem happened...
This time I tried taking out the Graphics Card out and connecting the monitor to the HDMI port in the motherboard, it worked just fine, so I assumed the problem is with the card, so I took it to my local service center, they said it was fine! So I took my whole tower to them and they tried it in front of me and it worked just fine! They used benchmarks that took the GPU usage to %100 and it didn't show any problems.
I've lost all hope in fixing this problem. My problem is that I don't know where the problem is.
Any help would be greatly appreciated.
Thank you all.
 

I tried the PSU, works fine.
My friend, however, recommended a very obvious solution which I hadn't tried. Reinstalling windows, and it worked! Not completely though.
It shows display now but after approximately 20 minutes it goes black and I have to restart it again.
I think this may be a software problem after all. Any ideas?