Desktop random hard shutdowns. Not PSU.

[jeffbidd44]

I built my first PC 6 months ago. It was working fine for the first month, then roughly around the time I moved to my new apartment I started experiencing random hard shutdowns. No BSOD or error messages. I can usually immediately power it back on with no problem. Some days it runs smoothly, then other days it will shutdown anywhere from 1 to 5 times.

Here's my parts list:
CPU: Intel Core i5-4460 3.2GHz Quad-Core Processor
Mobo: ASRock H97 Anniversary ATX LGA1150
RAM: Team Elite Plus 8GB (1 x 8GB) DDR3-1600
SSD (for OS): Crucial BX100 120GB 2.5" SSD
HDD: Western Digital Caviar Blue 1TB 3.5" 7200RPM HDD
GPU: Sapphire Radeon R9 280 3GB Dual-X Video Card
PSU: EVGA 750W 80+ Gold Certified Fully-Modular ATX Power Supply

I initially had a Corsair CX 500 PSU that I thought might be the culprate, so I bought the new PSU shown above and still got shutdowns. PSU doesn't seem to be the problem.

I took it to a PC repair store, and they ran stress tests and other tests for three weeks and it never shutdown. I thought maybe my apartment was supplying faulty power, so I bought a UPS. Still getting random shutdowns. I've tested it in different outlets around my apartment as well in other homes, and it has still shutdown. I ran it with no USB devices plugged in, case open, different outlet, no monitor plugged in, and it shut still down.

I'm just so perplexed and frustrated. Any help would be greatly appreciated.

 

[Outlander_04]

Describe exactly what happens when it shuts down

 

[jeffbidd44]

Describe exactly what happens when it shuts down

Everything suddenly turns off. It acts as if the power cord was pulled. No warning, error messages, or blue screen. The monitor stays on momentarily and says something like "No signal" and then turns off shortly thereafter. The PC doesn't restart on it's own; I have to manually restart it. It often happens even under low-load situations such as web browsing.

 

[Outlander_04]

OK so that is a sudden power cut to the mb

You have eliminated the psu and the wiring in your apartment
That pretty much isolates it to either
1/ demonic infestation
or
2/ the case power buttons shorting
[ though why this did not happen in the repair store I can not explain ]

Open the case . Take a pic so you can plug things in correctly later . Disconnect the leads to the front power switch and to the reset button.

Start the pc by shorting the power pins together momentarily with the tip of a screwdriver .
If it doesnt crash then you have found the problem

 

[jeffbidd44]

Thanks for your suggestion Outlander. I tried what you mentioned above, but it still shutdown about 12 hours or so later. At this point I'm beginning to think demonic infestation is pretty plausible.

I've read somewhere that the motherboard could be to blame for hard shutdowns if not the PSU. What are your thoughts on that? I hate to swap out a motherboard, but I am running out of options. I'm also wondering if I should run it outside of the case for awhile and see what happens.

 

[jeffbidd44]

I have an update.

I took out the graphics card and ran the PC using on-board graphics. It ran flawlessly for several weeks. I decided to RMA the graphics card; I received the replacement today. Within an hour of installing the new graphics card, I got more hard shutdowns. Completely random just like before.

So now it appears that I only get random shutdowns when a GPU is plugged in. Is this a motherboard issue?

 

[Outlander_04]

The way it shuts down indicates a sudden power supply cut . Almost all other issues will blue screen and give an error warning.

Obviously when the graphics card is installed you are using much more power so that suggests that somewhere in your set up is a limitation that cannot handle the extra load . You have eliminated the psu itself by completely changing it . Maybe its time to start looking at the wiring supplying the pc . Do you use a power strip to connect everything?
Try another . Try a power socket in another room . Try disconnecting all other peripheral devices to lower the load .

 

[jeffbidd44]

I replaced my motherboard with a new one of the same model, and since then I haven't had a single shutdown. It's been running smoothly for the past 2 months or so. Whether it was the motherboard itself, or something I did in the process of replacing the motherboard, it seems to be fixed for now.