PC restarting - no BSOD

Hi, I posted here a while ago about a GPU upgrade I was making and whether or not my PSU could handle it. General consensus was that it would be fine and then some, so I made the upgrade and everything was. However, recently I've been having some unusual issues and I'm wondering whether it's a sign of my PSU dying, a motherboard issue or something else entirely.

Here is what happens: If I turn my PC off for an extended period of time (anything over 40 minutes so far), when I turn it back on - roughly 10 minutes later the power will die and it will restart. No warning, no BSOD and it doesn't matter what I'm doing; gaming or web browsing it still happens. Upon it rebooting itself it tells me my overclock has failed and gives me options to return to bios or wipe the overclock or return to last known good configuration. After this INITIAL reboot/shut down it won't happen again at all, until the next time I leave my PC off for an extended period of time - it's very odd, so long as I get that cold boot out the way everything is fine.

I have stress tested my CPU overclock overnight to ensure it was stable, I had zero errors and temps were fine (never went above 80c in Prime95). I've ran Prime95 and Furmark at the same time to ensure that my GPU and CPU weren't shutting down my PC in even the most stressful situations - both ran fine, no shutdowns.

Some of things I've tried:

- Re-seating the GPU and blowing any possible dust out the PCI-E slot
- Ensuring all motherboard connectors are properly 'in'
- Checked all temperatures
- Ensured the PCI-E Connectors for the GPU are in correctly

Specs:

CPU - i5 4690k @ 4.6 1.16v
Mobo - MSI Z97i AC (mini ITX)
Ram - 8gb Corsair Vengeance
GPU - Galax GTX 970
SSD - 120gb Samsung 840 EVO
HDD - 1tb WD Blue
PSU - 500w EVGA 80+
Other random things: NZXT Sentry 2 Fan controller + 4 fans, few USB Peripherals.


Any help would be greatly appreciated, I just can't see why after an initial boot it's almost always 10 minutes later it shuts down then after that never does it again until the NEXT cold boot.

Does it do it at stock settings (no overclock) ?

Mr.Scott said:

Does it do it at stock settings (no overclock) ?

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It does it at 3.9ghz (Turbo mode always enabled). I'll reset everything to defaults now (without forcing Turbo) and leave it off for 40 minutes and see what happens.

That's a REALLY low voltage for 4.6GHz

How old is the PSU? Have you checked it with a multimeter?

ATMINSIDE said:

That's a REALLY low voltage for 4.6GHz

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That's what I was thinking.

Well I've had a look around, specifically reddit.com/r/overclocking and it seems relatively common for people who did well in the ol' silicon lottery. Plenty of people running similar voltages/speeds to me (obviously same CPU) and seemingly no issues. For what it's worth I tried it at 1.2v (still 4.6ghz) and the same thing happened, should I up it some more?

Currently I've just turn my PC back on after an hour of being off (this is when the shut down happens) and I'm running full default settings, so let's see what happens - only been five minutes so far

Sorry for double post:

OK, so it's been about 20 minutes and no shutdown/restart. Where do I go from here? I'm pretty confused, overclock is stable in terms of overnight Prime95 (small ftt's) test and this has only started happening in the last two weeks - before that there was ZERO issues. This also happened when I set everything to default EXCEPT forcing turbo.

Thoughts?

Use Blend, not Small FFTs.

ATMINSIDE said:

Use Blend, not Small FFTs.

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I've done that too, due to checking whether my RAM was at fault, also ran Memtest.

ATMINSIDE said:

How old is the PSU? Have you checked it with a multimeter?

Click to expand...

Quoting it since you haven't addressed it yet.

ATMINSIDE said:

Quoting it since you haven't addressed it yet.

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Oh sorry, I actually wrote out a response to that earlier and my PC died haha. I have not checked it with a multimeter and it is 4 months old, maybe 5.

Go ahead and grab the multimeter, just to be sure.

ATMINSIDE said:

Go ahead and grab the multimeter, just to be sure.

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Forgive my ignorance, I have absolutely zero experience with these, would something like this be ok?

Yep, that'll do perfectly

let us know if it does it at all default settings please.

caddi daddi said:

let us know if it does it at all default settings please.

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I did, it's above - I said it didn't do it and thus I need advice on what to do next. It was suggested that I get a multimeter so that's my next port of call I guess.

Well, small update. It's still doing it, even at default settings. However, I have found another trait - if I shut down my computer then flick the switch on the back of my PSU so it's completely off, the computer is fine on next boot - absolutely no restarts. If I shut it down and leave it with the PSU passively taking current in, next boot it will black screen restart within 10 minutes regardless of CPU/GPU load or what I'm doing. Does this narrow it down at all?

Sounds like a bad PSU capacitor to me. Happens.

Robert17 said:

Sounds like a bad PSU capacitor to me. Happens.

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In the PSU or the motherboard? Also, is it dangerous - for the power to just cut out like that? When it goes off, it goes off almost like it's shut down but without the 'shutting down' part - if that makes any sense =/

PSU. Do you have a spare or borrowable PSU available to test the theory?