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My desktop computer recently started powering down without warning during normal operation. It's not the power bar or outlet the bar is connected to, because nothing else connected to the power bar powers down when the computer does. Then I thought it was the PSU so I purchased a new one going from 430W to 850W but after getting that installed today the computer powered off again a few minutes after booting. I've cleaned out the case with canned air, checked the connections and can't come up with a reason it should be shutting down.

Any suggestions for what I should be checking before I pay somebody to give it a once over?

You mean just suddenly turning off like it was unplugged? Besides the PSU the only other component that could do that is the motherboard. Any other part would cause a freeze or bsod.

What else is plugged into that power bar? Some appliances won't be affected by a fraction-of-a-second power loss, but a PC will.

Sudden shutdowns which are actual shutdowns not reboots are almost always heat related.

Everything else tends to cause a reboot.

Take the heatsink off, apply new thermal paste, and make sure the heatsink is seated properly and the fan runs cleanly.

@Dominus Atheos:

Exactly, it's just like somebody yanked out the cord.

@Zaune:

The powerbar is running my Cisco IP phone, a computer monitor, and a stereo, as well as my laptop. None of them seem to be effected by these power drops. I would expect that laptop to be, as its battery doesn't have enough juice to power it up but I suppose it could have just enough power left that it doesn't get shut down if there is a split second drop. I'll try bypassing the power bar after my shift is done and see if that helps.

I'll feel a bit silly for upgrading my PSU if that's the cause, but at the same time I've been considering putting a new graphics card into my computer and this spreads out that cost nicely anyway.

@Vendetta:

I thought that was the case myself at first, and I started by blowing all the dust out of the case and then vacuuming the case fans to make sure there was proper airflow. Then I verified that it wasn't the issue by running the program that came with the mother board and checking it against Speedfan. The temperatures aren't high enough that they should be causing any shutdowns unless the numbers being reported are completely off.

Have you checked the Windows Error Logs, it may be recording something of use when it shuts off.

@Luke Starkiller:

Not yet, but I can take a peak at them after work.

It looks like the IP phone was in the wall outlet and it was just the monitor, stereo, laptop, and desktop in the power bar. I've changed a few things around and will let the desktop run while I continue my shift on my laptop.

It looks like the power bar may have been the issue. The computer has been on and stable for about an hour now and while I haven't had it under any load yet I'm hoping that it was just an old power bar acting up.

I thought that the issue was fixed as the computer ran for 4 more hours after my last post, but then it crashed under nearly no load while I was playing the Pokemon TCG. Looking at the Windows Error log I'm seeing Kernal-Power errors but that doesn't tell me anything I didn't already know. So what I do know is that the computer ran fine for ~5 hours sitting on the desktop with nothing but Steam's login screen and the iTunes updater running, and then crashed after less than 30 minutes of me starting to use it while running only those programs with Chrome and the Pokemon TCG running.

Any ideas?

Run Crystal Disk Info. A hard drive that's starting to go bad can cause that sort of issues, though the total powerdown is probably the motherboard starting to decay. My previous machine did not run high temperatures, but the mobo still broke down of its own accord. Sound was the first to go, then random reboots and crashes and not starting up until I switched the SATA connection to a different port, at which point it was time for a new machine.

I hope it isn't the motherboard, I went pretty high end and have done my best to take care of the machine. If it is, I guess I'll need to grab a new one next month and use my laptop until then.

Here's something stupid to try...check the power switch. I've had more than one computer with a sticky or flaky power button that could cause all sorts of random power events.

Maybe a stupid question, but did you make sure the power supply was compatible with your motherboard before you bought it?

I mean there's issues like this: http://techreport.com/review/24897/the- ... ility-list

Borgholio wrote:Here's something stupid to try...check the power switch. I've had more than one computer with a sticky or flaky power button that could cause all sorts of random power events.

The power switch doesn't seem to be sticky at all, and it runs fine when left idle but crashes under any use, I honestly suspect something to do with the graphics card as it tends to crash faster when youtube or games are involved.

General Zod wrote:Maybe a stupid question, but did you make sure the power supply was compatible with your motherboard before you bought it?

I mean there's issues like this: http://techreport.com/review/24897/the- ... ility-list

The old Antec VP450 PSU worked fine for several years without issue and the new one is a high end Antect 850W High Current Pro Platinum that's fully Haswell compatible. I don't think that would be the issue in this particular case, though it's something I'll be more aware of from now on.

The power switch doesn't seem to be sticky at all, and it runs fine when left idle but crashes under any use, I honestly suspect something to do with the graphics card as it tends to crash faster when youtube or games are involved.

Does your MB have onboard graphics? If so, remove your video card and use the onboard one for awhile. Sometimes just removing components one at a time will help narrow down the problem. Also run Memtest to see if your RAM is having issues.

Did you check for swollen or blown capacitors?

Borgholio wrote:Does your MB have onboard graphics? If so, remove your video card and use the onboard one for awhile. Sometimes just removing components one at a time will help narrow down the problem. Also run Memtest to see if your RAM is having issues.

No, it doesn't have onboard graphics, would be nice in this case if it did.

Jaepheth wrote:Did you check for swollen or blown capacitors?

I did; I couldn't find any. However, I took some pictures on my phone so somebody with better eyes or a knowledge of what to look for might spot something.

Here's that gallery

I also have a plan of attack for getting to the bottom of things. Tomorrow I'm going to remove the CPU and flash the motherboard with the latest BIOS, it's a nice feature to be able to do this with nothing but the motherboard and PSU connected. Then with that done I'll have to install the RAM, CPU, and graphics card so I can boot it and ensure that the new BIOS is working as intended. With that done, I'll hook up the hard drive and transfer any files of value that I don't have stored elsewhere to a USB drive before formatting the drive. Then we can start looking at the issues with the latest BIOS, a clean install of windows 7, and naught else to get in the way.

I suppose I should also post a parts list in case that helps:

Motherboard: Asus Sabertooth 990FX R2.0
CPU: AMD FX-8350 Piledriver with Stock Cooling
Graphics: Gigabyte Radeon HD 7870 2GB Video Card
RAM: Corsair XMS 8GB (1 x 8GB) DDR3-1600 Memory
PSU: Antec 850W 80+ Platinum

I have no idea what finally resolved the issue because in terms of parts the only thing I ever swapped was the PSU, but my PC is back up and running again. I suspect that it may have something to do with running a very deep reformatting tool (the thing took 18 hours and 3 passes to be happy with the state of the formatting) and installing Ubuntu before wiping everything again and throwing a fresh install of windows 7 back onto it.