Question No signal after few minutes

[angardia]

After few days i didn't use my pc, i turned it on to use the browser.
Few minutes (like 10) later my screen went black showing no signal.
I heard the fans start working louder.
After few attempts to restart, the time before black screen and no signal became shorter
until i tried to turn it on and got black screen without even getting to desktop.
So far i went through all cables and checked if there is something loose, but everything is connected fine.
I switched the screen cable from dp to hdmi, same thing.
Any ideas what it might be?

Update:
Pc working only after full shutdown for few mins. If i restart, the screen is black.
I tried to see if safe mode helps, but after 2 minutes in safe mode black screen and even restarts added to the issue.
I changed monitors, didn't help.
I changed my evga gtx 970 to some old gpu and pc working for now.
But im not sure if PSU involved in this and switching to old card prevent it from crashing.
My PSU EVGA Supernova 750 G3, 80 Plus Gold 750W, Fully Modular, Eco Mode HDB Fan, 10 Year Warranty, Includes Power ON Self Tester, Compact 150mm Size, Power Supply 220-G3-0750-X1

 

[ffg7]

does the motherboard have onboard video & if yes does the onboard video port matches your monitor port? the reason i'm asking is to isolate the problem as i think it is evga gtx 970 videocard is the problem. how old is that card as maybe still under warranty?