[SOLVED] PC shuts down sometimes

Jan 16, 2022
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This problem started some time ago when i changed my case.
When i try to turn on my PC, the fans start, the PC stays on for 2 seconds and then it shuts down making a weird, low and acute electrical noise. After that, the PC turns on by itself, stays on for 2 seconds and then the procedure repeats over and over again (it doesn’t stop unless i turn off the PSU). This is something that just started happening just after changing my case (i don’t think it was that). I am not sure of the cause but i believe it’s the PSU malfunctioning, so i did some testing. I used a PSU voltage tester and it was all normal, maybe it is a short circuit or some electrical issue i don’t understand.

Also, i have noticed that when i unplug the CPU cable to the motherboard and try to turn on the PC, it works just fine, the fans start and just stay on as long as i want (of course nothing works because the CPU is lacking :p), but maybe there’s the problem, i am not sure.
The weird thing about all these is that only happens sometimes and not always (usually when i unplug my PSU and then plug it and try to turn on my PC). I can’t find a pattern and i don’t know what’s wrong with my PC. What do you think the issue is guys? I would really appreciate if you could give me a hand.
 
Ok. What you're experiencing is because you're cutting the power at the PSU. It doesn't do this when you shut down from Windows and turn back on from the case power button, right?

You're cutting +5VSB to the motherboard by flipping the switch. This is clearing your XMP settings for your memory so when you turn the PC back on, it has to cycle through different iterations of memory timing until it can find something stable.

On your board, it's called "Memory Boot Mode". It "learns" the timings every time you power up your PC after a power loss.

Why are you always turning your PC off from the back of the PSU?
 
Jan 16, 2022
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The best place to start would be a complete list of specs.
Yes sorry, i have:
  • i5 9400F
  • MSI 1660 Super
  • Gigabyte H310M M.2 2.0 motherboard
  • 16GB RAM 2400 MHz (2x8GB)
  • 240GB M.2 (O.S.)
  • 1TB HDD 7200rpm
  • Cooler Master 550W 80 Plus Bronze MWE V2
  • 4x 120mm ID Cooling case fans
  • 1x ID Cooling CPU Cooler SE-903
Is that complete enough? I may be forgetting something.

Edit: forgot the case, it is Thermaltake S100 White
 
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Jan 16, 2022
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So the ONLY THING that changed was the case?

Maybe when you put everything in the new case, you shorted out the motherboard or pinched a wire causing a short?
Exactly, the only thing that changed was the case (and 2 additional ID Cooling case fans). About the wires, they all seem fine and i took out all the seals just in case.
 
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Jan 16, 2022
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Did you check positions of motherboard stand-offs,
I just checked, nothing seems to be making contact with metal and in a good position. This is weird because right now my PC is alive and kicking, and this only happens sometimes (usually after i turn the power off completely from the PSU).

Edit: rn i need the PC for work but this weekend i will re-install the motherboard just to make sure.
 
Jan 16, 2022
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Are there spacers between motherboard and case?
Yes, i didn't have to use any of the golden ones because the case already had enough embedded, so i just screw my motherboard there.But yes, there is a separation between those two, although the spacers are not the golden ones.
 
I just checked, nothing seems to be making contact with metal and in a good position. This is weird because right now my PC is alive and kicking, and this only happens sometimes (usually after i turn the power off completely from the PSU).

Edit: rn i need the PC for work but this weekend i will re-install the motherboard just to make sure.
Wait.... So the PC actually works?

So what's the problem again?
When i try to turn on my PC, the fans start, the PC stays on for 2 seconds and then it shuts down making a weird, low and acute electrical noise. After that, the PC turns on by itself, stays on for 2 seconds and then the procedure repeats over and over again (it doesn’t stop unless i turn off the PSU). This is something that just started happening just after changing my case (i don’t think it was that). I am not sure of the cause but i believe it’s the PSU malfunctioning, so i did some testing. I used a PSU voltage tester and it was all normal, maybe it is a short circuit or some electrical issue i don’t understand.
This implies the PC isn't working.

Can you start over again?

And when you use terms like "turn on my PC", are we talking about switch on the back of the PSU then the case button? Just the case button?
 
Jan 16, 2022
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Wait.... So the PC actually works?

So what's the problem again?


This implies the PC isn't working.

Can you start over again?

And when you use terms like "turn on my PC", are we talking about switch on the back of the PSU then the case button? Just the case button?
Sure! I will explain it better and with more details, sorry. The problem:
So, there is no actual problem right now because i can use my PC (currently), but i am afraid that either some electrical issue may damage some component in the future or that some day i may need the PC and i am not being able to use it because it doesn't start. This has happened several times since i changed my case (if it was a one time thing i guess i would just turn a blind eye haha).

So, the steps are the following:
  1. I turn the PSU switch on
  2. After 5 minutes i turn the case switch on
  3. The fans start, everything seems normal for 2 seconds
  4. After that, the fans stop spinning and the PC turns off by itself while making a weird, low and acute electrical noise
  5. As soon as it turns off, it turns on by itself (with me doing nothing), and the process repeats over and over again unless i turn the PSU switch off
Some weird things i have noticed:
  • When i unplug the CPU wire from the motherboard and try the process above, the PC never turns off and 'works' (of course the PC doesn't work without CPU, but it stays with constant power)
  • If it happens, it happens after the PSU switch was off for some time
  • Another strange thing that happens to me is that this only happens sometimes, after the PSU switch was off for some time (for example, right now i am using my PC and nothings seems out of place)
  • This never happened to me before but just after i changed case
What i have tried:
  • When this happened, i tried turning my PSU switch on and leave it like that for 10 minutes before trying to turn on my case switch
  • I also checked the motherboard standoffs as you guys told me but i couldn't find any issue there, also there's no contact
  • I tried unplugging the CPU power wire as said above, and when i turned my case switch on it didn't shut down by itself, it just kept 'functioning' (i use ' ' because it doesn't really functions without CPU)
  • I used a PSU voltage checker to check if voltage was fine (it was, so i concluded that either the problem is within the PSU and it is some cable shortcut, or that actually the PSU isn't the problem)
Again, sorry if my previous explanation wasn't good enough, i hope this helps more.
:):):)
 
Jan 16, 2022
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Ok. What you're experiencing is because you're cutting the power at the PSU. It doesn't do this when you shut down from Windows and turn back on from the case power button, right?

You're cutting +5VSB to the motherboard by flipping the switch. This is clearing your XMP settings for your memory so when you turn the PC back on, it has to cycle through different iterations of memory timing until it can find something stable.

On your board, it's called "Memory Boot Mode". It "learns" the timings every time you power up your PC after a power loss.

Why are you always turning your PC off from the back of the PSU?
That's so cool. You are right, it doesn't happen when i do it from Windows.

Well, i don't cut the power from the PSU switch on a daily basis, i just do it when i know i won't be home for a long time or i am on vacation. So this problem doesn't actually happen too often, just once in a while, but the other day, for example, i had to move data from my dad's internal HDD to mine, so i turned off my PC from Windows, and after that i turned the PSU switch off, unplugged the power cable and peripherals, and opened my PC just to connect the HDD. So i did that and this issue appeared again (it hadn't happened for a long time). It entered in the cycle (i believed the cycle meant my PC was about to explode :sweatsmile:) and the only way i found to break the cycle was to turn off the PSU switch and then turning it on again (and touching the case power button), with the hope it worked. Amazingly it did work after some attempts, but i wasn't able to understand the cause.

So, what would be the long term solution to this? Thank you so much!

Edit: i also got power cuts and variations in tension since here in Argentina when it's too hot, the electrical power system collapses.
 

Zerk2012

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That's so cool. You are right, it doesn't happen when i do it from Windows.

Well, i don't cut the power from the PSU switch on a daily basis, i just do it when i know i won't be home for a long time or i am on vacation. So this problem doesn't actually happen too often, just once in a while, but the other day, for example, i had to move data from my dad's internal HDD to mine, so i turned off my PC from Windows, and after that i turned the PSU switch off, unplugged the power cable and peripherals, and opened my PC just to connect the HDD. So i did that and this issue appeared again (it hadn't happened for a long time). It entered in the cycle (i believed the cycle meant my PC was about to explode :sweatsmile:) and the only way i found to break the cycle was to turn off the PSU switch and then turning it on again (and touching the case power button), with the hope it worked. Amazingly it did work after some attempts, but i wasn't able to understand the cause.

So, what would be the long term solution to this? Thank you so much!

Edit: i also got power cuts and variations in tension since here in Argentina when it's too hot, the electrical power system collapses.
You have a power grid problem not a PC problem and stop turning the power supply off.

EDIT might need to invest in a UPS
 
Jan 16, 2022
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You have a power grid problem not a PC problem and stop turning the power supply off.

EDIT might need to invest in a UPS
Apart from not turning the power supply off can i make something else that prevents this from happening? Sorry if i don't understand much about all these things, i am new in the hardware world.

Yes, eventually i want to buy an UPS with tension control. Also, where do you guys learn about hardware? It seems interesting to me and i want to learn more.
 
Edit: i also got power cuts and variations in tension since here in Argentina when it's too hot, the electrical power system collapses.
Stop unplugging your PC. ;-)

Power cuts aren't going to hurt your PC if it's off. If it's on, of course, then you lose what you're doing. If you want to solve that problem, you get a UPS.

If you have power spikes, like from power spikes from lightning, you need a good surge suppressor.
 

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