Computer turns off after 15-20 minutes

[Benj M]

My computer keeps on shutting down.

At first the problem was it won't boot. The motherboard HDD and VGA LED light will stay on. Then I took it to a computer repair shop. They told me my onboard graphics doesn't work anymore. So I bought a new GPU and it would successfully boot but after 20 minutes or so it would just turn off without warning, no BSOD whatsoever. Whether I'm playing games or just sitting idle on the desktop it would turn off. I tried monitoring the temps but it would stay within normal leves. Max was about 60°c and average was like 40°c.

Before it turns off a *tick* sound can be heard behind the PC. So I taught it was the PSU which is probably the problem. So I bought a new PSU. It would work for the same amount of time before it too shuts down without warning. Just black screen and fans turning off. I tried touching the PSUs and the heat sinks if it feels hot but they are not hot. So I don't think it's a temperature issue. Also the whole case is clean and the thermal paste is new.

What could be the problem? I really need my desktop for school and I'm running out of options and funds. Thank you in advance

Procie: Intel i7 4770
Mobo: Asus B85 pro gamer
Ram: Corsair 4gbx2 1600 1.5v DDR3
HDD: Seagate Barracuda 1000gb
GPU: Zotac 1050 mini 2gb DDR5
PSU: Antec truepower 750w and DeepCool DE-500 500w peak
Case: CM Storm Stryker

x1 200mm exhaust
x1 120mm intake
x2 80mm intake

 

[RARRAF]

download the latest bios from asus for your motherboard put it on a usb stick reboot enter the bios by hammering the delete key leave the system in the bios for 30mins say so no shut down. System is stable in the bios now insert the usb with the bios on it reboot machine and go into system bios update and flash your bios it should only take 2-3mins do not exit until completed as this could brick your motherboard. hopefully the new bios will fix the issues you were having.

 

[Jwpanz]

It sounds like something is shorting inside of your PC. The only time I hear about this sort of thing happening is when a power cable from the PSU is plugged into the wrong place or if a motherboard is dead. In your case, it sounds like that dead on-board video may be the case. Your motherboard may be damaged and a short may be occurring inside of it. My advice is to swap the motherboard out for a new one.