Help: Complicated power problem

N

NewBuilder

n00b
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Oct 9, 2015
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Seemingly complicated power problem but I don’t think it’s the PS unit. New builder so hope someone can explain to me why it’s a simple problem. All components bought new in the past few months.

Computer powers off suddenly (not goes through the shutdown procedure, but just shuts off) at seemingly random times. Neither case nor PS feels warm, lights don’t dim, UPS set at high sensitivity doesn’t trip. Sometimes it turns itself back on again after a few seconds and goes through the standard boot up. My system does not draw anywhere near the PS’ max rated power. Sometimes I have to press the case power button to get it to turn on again. Sometimes I press the button and it turns on for a second (my desk light dims slightly and the power light comes on, CPU and case fan spin) before shutting off again. Then nothing happens if I press the button again (won’t come on at all, no desk light dimming) unless I unplug PS from outlet and plug it back in again. Then sometimes same power on for a second, not long enough to post to the monitor, and sometimes nothing at all when I press the button. Or sometimes it will come back on again normally, especially if I wait a few hours, when I press the button. Sometimes still won’t come on normally even if I wait a few hours. No difference if I use a regular power strip rather than the UPS (got the UPS in hope it would solve problem). Running Windows 10, not running Prime95.

Usually goes for days, at least, in between bouts of this problem.

Swapped out my EVGA PS for a new Corsair RM850i. Used new cables for MB and CPU power. Then when I would press the button, it would draw power (light dimmed), but only CPU fan would spin and the power light on the computer would not come on (yes, case fans plugged in but the one I could see easily would not spin). Subsequent pushes of button did nothing (no power draw) unless I unplugged PS and plugged it in again. Never could get it to power on over the course of 24 hours with the Corsair. Put the EVGA back in and it powered on immediately, but still have periodic shut-offs.

Green power LED on MB always comes on when either PS plugged in, never shuts off, but none of the red LEDs come on during the one-second power ups, not enough time. Computer behaves normally when on.

Unplugged power switch cable and other little case cables from MB and plugged back in when I put the EVGA back in. With the HDD LED plugged back into the right place, computer would shut off when I held down the power button but then turn itself back on again a few seconds later. Now have HDD LED plugged into the wrong place and don’t have that problem (nor a light when the SSD is in use).

If it’s the case power switch, why does unplugging and replugging the PS matter? Have tried jostling the case without unplugging but that doesn’t work. If it’s the PS, why didn’t replacing it help? In fact, why did it not power up at all with the new PS? I don’t know if it’s the MB, CPU, or something else and not sure how to find out without going through the expensive and time-consuming process of replacing each component. Thanks for any ideas.

Build:
Asus Z170-A
i7-6700K
MSI GeForce GTX 970
Crucial BX100 500G
Pioneer Blu-Ray BDR-209DBK
Noctua NH-D15 CPU cooler
Crucial Ballistix Tactical 16GB (2 x 8GB) 288-Pin DDR4 SDRAM DDR4 2666
Nanoxia Deep Silence 3 Mid Tower Case
EVGA SuperNOVA 850 B2 80+ BRONZE, 850W Semi Modular

UPS:
CP1500PFCLCD
 
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try pulling it out of the case and running it naked on the bench for a few hours, sounds like an intermittent case short to me
 
Problem is, it can go for days or weeks without the problem occurring. Maybe I should try transplanting to a different kind of case? Or is there a way to avoid hooking it up to the case power button but still be able to power it on?
 
a customer of mine had the same kind of issue it was his battery back was crapping out plus his power settings inside windows ( control panel power options) were set to turn the pc off after 30 minutes he plugged directly into the wall with no battery back , changed the power option inside windows and never called me back......:)
 
NewBuilder said:
Problem is, it can go for days or weeks without the problem occurring. Maybe I should try transplanting to a different kind of case? Or is there a way to avoid hooking it up to the case power button but still be able to power it on?
Click to expand...

yes, you can short those pins with the tip of a screwdriver, or hook up a momentary switch salvaged out of an old case
 
NewBuilder said:
Computer powers off suddenly (not goes through the shutdown procedure, but just shuts off) at seemingly random times.
Click to expand...

Bad RAM can do this. Run multiple instances HCI Memtest, which is generally a better memtest than Memtest86 or Memtest86+ (though no software RAM tester is perfect).

If you find the RAM to be bad, update the motherboard's BIOS and retest. If you get no errors on the RAM tests, update the motherboard's BIOS anyway, because I see that for your motherboard, in the last 2 months there have been several "improve system stability" updates which could mean anything, including potentially your issue.
 
jojo69 said:
try pulling it out of the case and running it naked on the bench for a few hours, sounds like an intermittent case short to me
Click to expand...

It could be many things as mentioned here, but this one came to my mind as well,
some type of intermittent case short.

Pull the mobo and recheck all of the stand-offs. Make sure there are no stand-offs
in the case that don't match up to a mobo mounting hole. I've seen experienced
techs make that mistake.

Also look for loose screws under the mobo that may be rolling around.

Take a look at the metal IO shield and make sure none of the metal grounding
fingers are stuck inside a USB port or something. Saw that one a couple of times.

That's all I have so far.... kind of strange the change in symptoms with change of
PSU but still similar failure mode.

Agree with quoted post that partial or intermittent shorts can cause this behavior.

Partial shorts can draw a lot of power and cause a burning smell too.
Any burning smells?
 
No smells, no desk lamp dimming except on startup, no UPS trips. It's working at the moment and will try bios update and mem test.
 
Updated bios to ver 1402, then ran 4 copies of hci memtest simultaneously for 55 minutes, no errors. If problem recurs, will try taking everything out of case, poking around for screws, and then replacing.
 
Check the stand-offs too, that's critical.

The stand-offs are all grounding points on the bottom of the mobo. If you have a stand-off out of place where it's not at a mobo mounting hole,
then it's grounding some random spot on the mobo. It could be hitting some point on the mobo that can't be grounded.
 
Problem recurred, so I took out the MB. Two stand-offs were missing and I found one in a part of the case not touching any parts, but perhaps it was the problem. I put in the two missing stand-offs and put one leaf of an anti-static bag behind the MB and also checked the I/O cover to make sure prongs weren't going into odd places. It's too soon to be sure this worked but I'm calling it solved. Thank you to everyone with suggestions, especially Spartacus, I'm very green.
 
Glad that was the issue.

I would not use the anti-static bag under the mobo. The anti-static bags are treated to make them CONDUCTIVE.
That's why they are anti static. Don't let powered up electronics touch anti-static bags.

Besides, the mobo is supposed to be touching the stand-offs at the mounting holes as grounding points.

Just remove the one stand-off that's in the wrong place, they unscrew very easily.
 
Ah. Some folks in other forums said they used anti-static bags and they helped. Will remove mine and see what happens.
 
NewBuilder said:
What about putting a layer of plastic tape on the case beneath the MB, for insulation?
Click to expand...

You can if you want to, but that should not be necessary.

If you actually had a long component lead on the bottom of the mobo that wasn't clipped in manufacturing, it would be wise to trim that off.
Please be careful with that though.... maybe post a pic of it here before trimming anything.

I actually had to do that on an old ASUS mobo last week when I mounted a new cooler on the CPU. Some of the leads on the bottom of the
mobo were a bit long in the CPU area and looked like they could touch the new backplate for the cooler. I carefully trimmed off a number of
them for better clearance on the backplate.
 
Still having problems. So took out anti-static bag and looked for long leads. Still no luck. Now have MB out of the case on top of a large book and everything disconnected except the PS to MB and CPU, video card out but RAM in. Using a new power switch, same issue of coming on for a second only (CPU fan spins for a moment). MB power light stays on but red LEDs never come on. Does it have to be the MB or CPU now? Which?
 
I had this very same issue just a short while ago.

My 4 year old ASUS Rampage Formula X79 did the same thing.

I never really confidently isolated the problem, but my testing narrowed it to the PSU or the MB.
I replaced both and have no further issues, I reused every other component in the PC.

What you have done so far:

removed the MB and placed it outside the case.
tested RAM.
installed a new BIOS version.

You need to do the following:
remove and replace the MB battery
test your GPU
reseat your CPU and HSF.

If all this fail to correct the problem and the components are functioning normally, then I'd replace the MB.
 
Okay, thanks, we'll see. I'm guessing I will have to replace the MB however. If I get the same model, my understanding is that I don't need to do a clean install or anything in software at all, just swap parts.
 
NewBuilder said:
Okay, thanks, we'll see. I'm guessing I will have to replace the MB however. If I get the same model, my understanding is that I don't need to do a clean install or anything in software at all, just swap parts.
Click to expand...
I just went from a X58 system to a Z170 system and didn't reinstall Windows 7 and everything worked fine (I didn need to install new drivers). Although it is a good idea to reinstall windows when doing something like that.

I'd say try an RMA with Asus to see if they can swap it for free under warranty, unless you think you did something to void your warranty. If you can't get fixed under warranty, then get whatever motherboard you want.
 
NewBuilder said:
Okay, thanks, we'll see. I'm guessing I will have to replace the MB however. If I get the same model, my understanding is that I don't need to do a clean install or anything in software at all, just swap parts.
Click to expand...

I'd like to think that was the case, too.

But it's like buying Levi's, two identical sized pairs fit ever so slightly different.

I always load up a new MB clean, even if it's the same model.
That way if something does go wrong, you have one less piece to worry about.
 
I think I might have used another power cable from another device, so I went and got the heavier-duty one that came with the Corsair. Now it's working. It's bone-chillingly stupid of me not to have tried another proper wall power cable before. However, it sometimes takes days or weeks for the problem to recur, so I'll see. Also, there is a chance that all my removing and reinstalling components did the trick instead. I'm calling this solved for now. Thanks.
 
I'm always really careful to only use the power cord for a device that it came with, and that goes double for power supplies and monitors.

Sure, they all look like the same generic C13 power connector, but if you ever have to RMA something, sometimes they are very particular about wanting you to try using the power cord it shipped with if you weren't using it, or shipping it back with the original power cord if you did use it.
 
Ah, I meant that when I tried replacing the power cord, I didn't use one that came with a PS. Now I am using the cord that came with my replacement PS (the Corsair) with my original PS (the EVGA, which I put back in after replacing it with the Corsair didn't work). If any power cord is defective, it's the one that originally came with the EVGA.
 
I'm happy I could help out.
However, this sounds too good to be true.

I would use a shotgun approach and also have a qualified electrician check your breaker box and the breakers themselves.

You have a pure sine wave UPS so it should be the right one for APFC PSUs. And while I sincerely hate cyberpower (But would trust 'dumb' APC units with my life support equipment), this one looks beefy.

Anyway enjoy your setup!
 
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Also I'm with evilsofa on this one. You have a 'gremlin' class problem, i.e. like you said it will come and go.

Do you have a multimeter? It's not the best of tests but try measuring resistance of each wire - from one end to the other. All three. Safety, Line and Ground. (sorry for the nomenclature, not familiar with US terms). Set it to '200' (ohms) and have a gander. My random PSu cable shows 0.5 ohms on all three leads.
I then would set it to thousands/millions and check if there is no contact between individual leads. If one of the leads is off in continuty, or if the meter somehow reacts when testing lead against lead - it's trash time. Feel free to wiggle the cable around with the meter leads connected and see if there's a kink.
Also, if there's a problem with the PSU cable, it should get warm - either PSU side or mains side or somewhere in between.
Spray some cleaning agent into the C13 holes, check for scorched points.
If the 'bad' cable passes this test, then it's probably too early to celebrate :( 'gremlins' tend to disappear for a while when you change something but usually come back...
 
Updating video card driver, and one of the things its says (GeForce Experience 2.9.1) is, "Fixes an intermittent GPU power state fluctuation on idle system." Since the machine powers off within a second or two of my pressing the on switch, I assume that it can't be a software problem.
 
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