Why does my computer not show anything on screen?

Jakob Brogaard

Honorable
Aug 12, 2013
2
0
10,510
So I recently bought a new computer, put it together yesterday, got it running without any problems, installed everything necessary and went for dinner. I left the PC running to finish some game downloads, and when I came back the screen didn't seem to respond at all. I tried unplugging my HDMI cable, turning on and off my screen, then PC. I still couldn't get it to work, and tried plugging my HDMI cable into my laptop. It did show a picture, at which point I got nervous that something had broke for some reason. I turned off my PC, went to the living room and plugged it up to that screen instead. It still doesn't work.

Mind you, I had it working but now it won't work. What could I do?

My GPU: AMD Radeon HD 7870
My screen: MIRAI DTL-722P302
My OS: Windows 8 Pro
 

Jakob Brogaard

Honorable
Aug 12, 2013
2
0
10,510


Full specs:

ASRock B75M-DGS
Intel Core i3-3220 Ivy Bridge - Box
XFX Radeon HD 7870 Core Edition - 2GB
Kingston HyperX blu DDR3-1600 DC - 16GB
SanDisk Ultra Plus SSD Desktop
Toshiba DT01ACA - 1TB
Cooler Master Elite 342 Black
Corsair CX750M - 750W PSU

Edit: Forgot to mention my PSU is brand new.