I have a Windows 8.1 custom PC that I built about 6 months ago. It worked great for several months with no problems, but about three months ago it started to reboot randomly.
My computer works fine for about twenty or thirty minutes, but then the screen will go black and the computer will restart. After the first reboot, my computer will restart before reaching the Windows loading screen and will keep restarting until I turn it off. If I turn it off and wait twenty minutes before turning it back on, my computer will run normally but after twenty minutes it restarts and everything starts all over again.
I noticed the computer only reboots when its running in Windows. I ran the computer in BIOS for several hours and it didn't reboot. I also noticed that sometimes it won't reboot if I just let my computer sit idle in Windows, but it always reboots when I run a program or app, even if the app isn't resource heavy.
Motherboard: Asus M5A99X EVO R2.0
CPU: AMD FX-8320 Eight-Core
Memory: Corsair XMS 3 DDR3 RAM (2 Sticks, 4GB each)
Graphics Card: AMD Radeon R9 270
Hard Drive: Hitachi HDS721050CLA362 500GB
Power Supply: Corsair Enthusiast Series TX650M (650W)
Optical Drive: DVD/CD-ROM Combo Drive
Case: Corsair 500R
I've done a few things to figure out what's wrong. I ran Memtest86+ to check my RAM, and it passed with no errors. I also monitored my CPU's usage, load and temperature using Task Manager and CoreTemp, and everything was normal right before the computer restarted. My CPU temperature was normal, always near 30°C to 39/40°C (the maximum temperature for my processor is 90°C) and the load was at most about 30%, so I don't think my CPU is the problem.
I ordered a psu tester to check my power supply. If the PSU is fine, then I might send my motherboard in for an RMA. I also thought about testing my hard drive, or running Prime95 but I haven't yet since my computer won't stay on for more than 30 minutes.
Does anyone have an idea what the problem is? Can I do anything else to test my computer?