PC powering off unexpectedly

Avenger1324

Avenger1324

Avenger1324

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Looking for some help as to what to look for next as I'm running out of ideas.

Right now I can get at most 10mins of seemingly normal use before it switches off instantly with no warning. It doesn't seem to matter what I am doing - just with Windows loaded, or even had it power off just while in BIOS.

Intel i7-2600K (stock)
Gigabyte GA-Z77X-D3H
16GB (4x4) Corsair Vengeance DDR3 1600MHz
Gigabyte Windforce GTX 670 2GB
Coolermaster 700W Silent Pro (swapped to Corsair RM1000x)
Samsung 850 EVO 1TB SSD + 2 x 1TB 7.2k HDDs
Windows 10

Starting a few months ago I could use my PC normally no problem until I shut it down. Then if I tried to start it again it would be temperamental. Sometimes it would start, sometimes get absolutely nothing. As I have seen from other threads pulling the power cord, pressing power a few times and plugging back in usually did the trick. (It did sometimes fallover in Dual BIOS, but a thread here about power+reset to clear corrupted BIOS worked to resolve the dual BIOS issue.) I tried updating my drivers and updated the BIOS, but still had the same issues.

Originally I was using a 700W Coolermaster Silent Pro PSU, but had managed to grab a Corsair RM1000x for a future build from Maplin while they were closing down. Suspecting either PSU or mobo, and having a new PSU, I installed that. First couple of days everything seemed good, then we were back to needing to unplug from the mains to get it back on. Seems PSU not the problem.

Then a week ago for the first time it completely shutdown mid game with no warning, as if there was a power cut (but there wasn't). Since then the longest I have been able to get my PC to stay on is about 10 mins, then another instant power off. Sometimes it will choose to power back on itself after a minute, but while it may get into Windows for a few minutes, will power off again.

I was able to keep it on long enough to use HWMonitor to confirm temps are all fine. CPU 40-45C, GPU under 40C, harddrives and case temps 20-30C. No alarm bells there. Also seeing same sort of temps in BIOS. Using a TRUE 120 air cooler & 120mm fan. Just booting into Windows and leaving it there it will power off inside 10 mins so not even a demanding application running.

I found an identical model mobo on ebay (used, claimed working), moved everything over to it today, powered on and had 10 mins of "thank god it worked", before instant off and a flurry of swear words. It seems the problem is still here. New mobo had had BIOS reset by the seller, so not old settings interfering and I also went in to check them. It was updated to the latest BIOS already, and all setting back to stock / Auto, so should just work. RAM at 1333 rather than XMP 1600, but should be fine running slower for now.

Moved CPU to a new mobo. Cleaned off old TIM and applied fresh. securely remounted the heat sink and air cooler (TRUE 120). In the limited time I have had it running again HWMonitor confirms temps back in the original range albeit a bit higher due to current weather. If it was thermal cut off I would be expecting temps 90+, not < 40C.

Checked power connectors from PSU. 20+4 pin securely in on the motherboard. 4 pin next to CPU firmly in. 8 + 6 pin on GPU firmly in.

I tried removing pairs of RAM and retesting - same results - on for up to 10 mins then powers off. Swapped pairs, swapped slots, same results. Seems not the memory at fault.

Read in another thread about power button / reset button failing. Tried swapping the pins to reset button - powered on, still shut off a short while later. Removed the front panel from the system and jumped the pins - came on, and still powered off a few mins later with no front panel attached.

I'm running out of ideas as I can't think what is causing it. I can get it to power on and get into BIOS and Windows, seemingly fully functional. I don't see anything odd when I get there - no display errors, no temp warnings, and HWMonitor figures all appear as expected, until the screen goes black and the PC stops.

Any clues as to what might be causing this or what I can try next?
 
Seems like a tough one to crack. Have you tried removing the GPU and running on the iGPU just to eliminate one more component?
 
So you've ruled out the Motherboard, RAM, PSU and power button so far? Do as Vargas/theforce say to rule out every possible thing you can. If it still happens with everything disconnected then I suppose the only thing it could be is the CPU?
 
I disconnected the GPU and connected my monitor directly off the DVI on the motherboard.
I also disconnected 2nd and 3rd harddrives, but not primary SSD, and also an optical drive. Now only one device connected via SATA - the primary OS SSD.
I also disconnected anything else running off molex power from the PSU - mostly case fans.

Initially loaded into BIOS and left it there stable for 5 mins, then proceeded into Windows. Worked for about 15 mins, then instant shutdown.

I can remove the SSD and just sit in BIOS to see if it still happens, as it did previously shutdown while just in BIOS going through the screens checking settings.
 
Now with all drives disconnected, just motherboard, CPU, RAM & PSU.

Now it has decided not to power on at all - a symptom of the last week or so - after an unexpected shutdown it doesn't want to power on at all. I've tried unplugging from the wall, power button and reset a few times to discharge anything stored, then reconnect and try power. At the moment the best I get is CPU fan spins up for 5 seconds - not long enough for the screen to wake up and POST, then powers off. I've not managed to get more from it in the last 30m of trying and now 1:40AM, so will unplug it overnight and try again in the morning.

Checking the troubleshooting it mentions CMOS battery which I haven't replaced. I have one on my original board, and one on the replacement board - would be a coincidence if both were duds. I don't have a spare right now but can get one in the morning.
 
tried stripping it all out of the case and building it on a flat piece of cardboard or something else non conductive just to rule out something causing a short? unlikely I know but at this stage it's worth a try, assuming the bios battery replacement doesn't work out.
 
Sounds like you're having a nightmare.

The battery could be the reason if you have somehow managed to find 2 boards both with dead batteries. Maybe you're lucky :rolleyes: enough that its just the battery(ies).

Have you tried a different power cable or wall socket? What about using just 1 stick of RAM at a time? Seems ridiculous but at this point I'd be ruling out every possible thing I could since nothing else seems to be doing anything.
 
Replaced the CMOS battery with a brand new one - same results.
I moved it to a new wall socket - direct to the wall, no multi plugs, surge protectors or anything else off that socket - same results.
The new PSU came with a new kettle lead, but I have tried with both old and new - in original and new power sockets - same results.

Next will be taking it out of the case to eliminate that.

New build is getting closer to being an option - had wanted to hold out until new Nvidia cards were available, but also if this is working it will be handed down to family. Ideally this would have been something simple like a dead motherboard and for sub-£100 fix I can have a working machine instead of needing to also get them a replacement system.
 
now with everything removed from the case.

Motherboard on a cardboard box, PSU out of case attached with only the 20+4 motherboard connector and 4 pin CPU connector. CPU and 4x4 RAM still installed.

Powered on, into BIOS, but powered itself off within 3 mins.
Powered back on, tried adjusting XMP to 1600 to see if that would make a difference - lasted 5 mins, then powered off.

Swapped out power supply back to the original 700W unit.
Warning about previous failed settings, auto reverted memory back to 1333, but then booted back into BIOS and so far still running after 20 mins.
Had to use a desk fan to keep some cooling across the board as PCH (northbridge?) and system temps were creeping up. Currently everything reporting steady at 34-37C.

Going to leave it in this state while I get something to eat and see if it survives.
 
Okay this is atleast positive - 1h45m stable running in BIOS with the old PSU attached, so maybe the new PSU is faulty?

Next steps would be putting it back into the case and re-introducing components, checking each for faults coming back.
 
Thats good news, and its strange - but there must have been an underlying issue with the old PSU to prompt you changing to the new one. So i'm not sure that youre totally in the clear yet :confused:
 
Avenger1324 said:
Okay this is atleast positive - 1h45m stable running in BIOS with the old PSU attached, so maybe the new PSU is faulty?

Next steps would be putting it back into the case and re-introducing components, checking each for faults coming back.
Click to expand...
At no point previously did you try switching back to the old psu?!
I’m a tad confused. I thought you changed psu’s because of powering off problems?
 
The original issue was to do with it not powering on after a successful (intended) shutdown. Original PSU and motherboard. Figuring that the issue was either to do with power or motherboard, and I had a new PSU to hand, that is why I put the new PSU in. After a few days of use the same issue came back - while it was on it worked fine and shutdown fine, but trying to power back on was a problem. With that new PSU installed I was able to have my PC running 6+ hours under load without issue until just before last weekend when it shutdown unexpectedly and would not power back on. If left for an hour or so, unplugged, power button a few times, then plugged back in it would power on, but then have unexpected shutdowns in 10-20mins.

I must admit I assumed the new PSU to be good, so bought a replacement motherboard, which arrived yesterday and installed yesterday afternoon. Yesterday all full system tests were done just with the new PSU in, now testing with the old one. Maybe should have put the old PSU back in earlier, but the combination of original PSU and original motherboard would have the original issue of powering on (though possibly not the unexpected shutdowns which are since the new PSU). While power on and power off look similar, they could have different causes :(

With everything already in pieces I put my CPU and RAM back onto the original motherboard and testing with original PSU. What I can now see in BIOS, but not prev in HWMonitor, is PCH temp is 20C higher than CPU or system temp. CPU and system temps reporting 35/36 as the new board did, but PCH on old board now showing 56C where the new board reported same as the other two. That might be an issue with the old board, but wouldn't explain why the new board would shut off suddenly unless that was caused by the new PSU.

EDIT - clearing a corrupted BIOS had reverted back to a much earlier revision. Reflashed to the latest non-BETA BIOS and temp reporting back in line - all 3 reporting the same.
 
Last edited:
Back up and running :)

Found a couple of things.

Don't assume because you did something before it's still like that :rolleyes:

Original motherboard. While troubleshooting issues a few months ago I had updated it to the latest BIOS revision as part of troubleshooting. What I hadn't noticed was that in doing a corrupt BIOS reset using power and reset buttons as described elsewhere on this forum, successfully fixing a UEFI Dual BIOS issue, it reverted the BIOS back to the earliest BIOS it had ever had, despite having had newer ones saved to it in both primary and secondary locations. So despite me starting this off with - yes BIOS is up to date, err... it really wasn't, and was possibly part of the issue here.

When I spotted the different BIOS a few hours ago, reporting very different temp readings, that could be part of the reason it would not want to power back on after an intended shutdown. The PCH temp reading was atleast 20C higher than CPU or case readings - the Northbridge heatsink however was not hot to the touch. Yet after the BIOS update the same reading is back in line. If something was overheating, or atleast the sensors thought it was, it would make sense that the system would not want to restart until components had cooled down to safe levels. Hopefully that's what that part was.


New PSU - with a totally stripped down system, on both new and old motherboard, setup on a box with nothing more than CPU (heatsink +fan) and RAM, couldn't maintain power just in BIOS. With everything else excluded from the setup, and now operational on the same components with my original PSU, I must suspect the new PSU. I can't return it where I bought it (Maplin), so this weeks task is sorting out RMA for it.

Now up and working fully in Windows for the last 2 hours, so hopefully that's back to normal. *fingers crossed*

Thank you for your help above - first time I've tried troubleshooting on just barebones with parts across a desk rather than in a case :)
 
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