Random reboot on old PC - what is dying?

[qbazdz]

Hi,

Wonder if anyone else encountered a similar problem and can speed up my troubleshooting please.
I've got an older PC (~10y old) with custom WC setup so a bit harder to strip down.
I had a replacement PSU from Corsair under warranty back in 2016 and since then the PC had had very occasional use (certainly fewer than 8hrs in a month, don't ask, it's complicated haha)

I started to use it more recently, did a few upgrades that suit me and done a fresh install of Win10.

Now, the actual problem is, that randomly the system will simply reboot, no warning, nothing simply instant power down and attempt to reboot. This very occasionally will succeed, but most of the time it will be stuck in the attempt to boot, fans will spin up and than it will die again and repeat.
Turning PSU off, de-energising the mobo and power up doesn't usually help (the moment you flick the psu switch it normally tries to boot without case power button being pressed), unless you give it 5-10min.
My Z68 Extreme 7 Rev 3 board, shows code corresponding with 'PEI Core is started' before it crashed after first one.

I suspect the PSU may be dying but it had so little use I am amazed this would be the case?

Any other ideas?
SSD is brand new, with all tests passing no problem.
I checked the battery voltage on the board - seems ok.
I didn't have any problems getting windows up and running, a number of time, had been using it for extended periods of time and this problem seems to be coming and going but its incredibly annoying!

Thanks

 

[qbazdz]

If you have a spare battery I'd replace it anyway.

Is it overclocked? Memory voltages and timings all okay?

What upgrades did you do?

Have you tried another SSD?

Its an old 2500K that run a small o/c when I needed it (say 8-9 years ago). Once I stopped using it regularly it was dialed back to stock.
DDR3 Memory has been running with its XMP profile since the built.
Most recently I had replaced the GPU (however the problem was present before hand) and prior to that I swapped 128GB old SSD for a new 1TB 860 Evo (this coincides with my increased usage and its hard to say if the problem was present before the SSD swap as I almost immediately went to set it up from scratch).

Just kicked off the Memory Diagnostic Tool from Windows, need to find a spare USB to run MemTest.

 

[qbazdz]

Quick update - Memtest86 run 4 loops, ~2hrs and found no issues.
I had a spare battery so swapped it again, was amazed to see that the replaced one already was down to 2.7V, a bit low but apparently functional for all the functionality safely.

Now I've got to deal with the stupid windows update which failed repeatedly (due to the unexpected reboots) and hasn't yet installed 21H2 properly an it keeps coming up with an error..

 

[qbazdz]

It shouldn't be too hard to get the power supply out of it.

Yes, except for all those cables that are neatly (*at least to some extent) organised in a tightly packed case

Ormy1
Defaults flashed, cables already re-checked twice, I even had the PSU once fully out to check with my external PSU checker by Antec
Temps had been absolutely fine, I even had done several loops of 3d Mark and Furmark once I got new GPU installed.

 

[qbazdz]

Reviving this again as I had been monitoring the situation over the few weeks with little progress really.

Had another look at the CMOS battery and thought it was a bit low and had a new one so replaced it just in case - CMOS clear and re-configured back to defaults.
@HangTime thanks for reminding me about event viewer - this showed almost nothing - certainly no events in minutes leading up to power being cut off, except for one particular process (think intel ISA) that was trying do do an update for it and failed to connect with the server.
After disabling it, I thought that would be it, however had another event last night while kicking some ass in MK11.. likely coincidental, but about the same time as my previous reboot. This time however nothing in the even viewer, so definitely not the process that had been the problem before..

Currently still can't for some reason successfully complete Windows Update to 22H2 as 21H2 fails.. I tried all possible fixes and will have to probably bite the bullet and do a clean install of 22H2 right off.

@Lee Monk, everything is clean - machine had a rebuild and a clean recently and new GPU has a water block and had also been cleaned before fitting.

Think I may try the PSU next, unless some good ideas come up?

 

[qbazdz]

@darael CMOS battery? or CPU Vdd? not sure if mobo has got test points for that

 

[qbazdz]

Sounds like a faulty motherboard.

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That is the type of behavior I get after it crashes, however why would it boot up after a while, as well as crashed after random times?

My current routine is normally to boot up - start up MK11U and be able to play for at least 30min before anything happens. Sometimes it takes longer.
I will still look around for leaking caps or anything on the mobo.

 

[qbazdz]

Perhaps you nudged the CPU cooler. Do you know the state of your thermal paste, or last time it was done? Thermal cut-out could be your problem, if it's no bulging/failing capacitors.

Its under WC, so unlikely, besides temps don't move past 40-45c under load. Ill try with a different PSU first.

 

[qbazdz]

Reluctance due to WC loop is understandable but after 10 years you have no idea what the paste is like under that block. Is your plan to never remove the cooling pipes?

Think you missed the info a bit earlier in the thread - I installed a new GPU recently and used it as a chance to drain and clean the entire build, including reseating of the CPU block.
Before and after I was running Furmark and other long term stability benchmarks without issues (temperature wise).

 

[qbazdz]

I was thinking of updating the thread before Christmas with some findings and good news.. I run a Prime+Furmark stress test for probably 3 hours+ without issues and was feeling confident problem is gone..
A day or two later, I must have turned MK11 for like 5 min and got reboots again - I was furious..

However, I think I have moved closer to finding the culprit, however not the solution yet!
As most of you suggested, this is 99.99% related to the PSU.. however not for the reasons we all thought.
I've got one of the funky Corsair AX860i which is famous for this problem - random shutdowns and bootloops. This is a fairly widespread issue, where apparently the cable PCA is susceptible to bend under stress and some caps on the edges may be suffering minor disconnections on solder joints.

I've pinged Corsair a ticket and we will see what they propose here.
Interestingly enough - I had been testing things and re-routed the PSU cables a bit, making sure to give them plenty of slack and also where possible, used the centrally located sockets..
Since than I must have played WoT for 3+ hours without an issue, although neither GPU or CPU were particularly stressed (2K, maxed out settings..) so perhaps this means nothing yet.