# [SOLVED]  Help needed - PC turns ON and then OFF in a matter of seconds



## ciotta (Jan 28, 2020)

Hello guys, i need help with a PC.
As soon as i turn it on (power button) it stays on for seconds and suddenly turns off again.

[EDIT]
the problem seems to be getting worse:
1st time it happened during windows boot
recently it was doing it during bios post messages
now it stays on for a fraction of a second and than turns off

[EDIT2]
when it truns off, it turns on again after 1 second, and than off in a fraction of a sec... let's hope it' just a mobo death loop

Tests i already made trying to turn it on:
x) heatsink is clean from dust
a) another PSU (info below)
b) single ram stick (both, single, inverted...), another slot (dual channel 1 and 3, 2 and 4)
c) check each and every cables, unplug replug all PSU connectors
d) unplug hard drive...
e) cmos reset (jumper), + no cmos battery for minutes
f) new cmos battery
g) tested with and without GPU.

HW specifications:
CPU i7
MB Asus Z97-Pro
RAM 16 Gb Corsair (2x8GB)
Cooler Corsair Hydro Series H80i GT Liquid CPU Cooler
GPU EVGA GT 740sc
SSD Samsung 850 Evo
PSU Corsair CX750M >> alternative for test Corsair VS 650

thank you for your time, for any othe rinfo feel free to ask. i hope we can solve this together


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## kapone32 (Jan 28, 2020)

Have you tried using a different GPU?


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## ciotta (Jan 28, 2020)

kapone32 said:


> Have you tried using a different GPU?


ops i miss to report the test... i tried with and without current GPU. Unplugged gpu video cable on motherboard.


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## basco (Jan 28, 2020)

so then there is only the cpu + mainboard left?


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## ciotta (Jan 28, 2020)

basco said:


> so then there is only the cpu + mainboard left?


yeah....i was hoping for something i was ignoring.
i can add that this problem seems to be getting worse:
1st time it happened during windows boot
recently it was doing it during bios post messages
now it stays on for a fraction of a second and than turns off (before bios post beep)


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## Hyderz (Jan 28, 2020)

could it be the cpu ?
1. dried thermal compound?
2. the heatsink not sitting properly causing it to overheat and shutoff

need additional info as well, e.g how old is it? when did it start happening?
im suspecting the motherboard be the culprit if the motherboard is old, maybe a circuitry malfuction somewhere


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## basco (Jan 28, 2020)

if you have a friend with changeable parts yes do it-but ya already did all the steps necessary for which i salute you!
hope y can solve it quick.  i had a z87 msi g43 and i hated it-my guess goes to the mb-in all my 30 years of computer i had one cpu die on me and that was my fault


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## ciotta (Jan 28, 2020)

Hyderz said:


> could it be the cpu ?
> 1. dried thermal compound?
> 2. the heatsink not sitting properly causing it to overheat and shutoff


I can doublecheck it but it does the problem after a fraction of a second now...overheating requires some time i think.



basco said:


> if you have a friend with changeable parts yes do it-but ya already did all the steps necessary for which i salute you!
> hope y can solve it quick.  i had a z87 msi g43 and i hated it-my guess goes to the mb-in all my 30 years of computer i had one cpu die on me and that was my fault



So you suggest to try another MOBO and if the problem is still there...CPU. K i will set my mind on it. Let's see if anyone has other suggestions. TY both


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## basco (Jan 28, 2020)

yeah you seem like ya know what ya do so not much to do there except mobo or cpu.
i salute you for doing all this stuff before asking bravo bravo.

last question: is it in a case?-if yes then make the simple out of case test with just the parts ya need for boot

sorry i thought its the mobo ya got in your sig-but its a Asus Z97-Pro which should be better then the msi low end stuff i had


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## ciotta (Jan 28, 2020)

Hyderz said:


> need additional info as well, e.g how old is it? when did it start happening?
> im suspecting the motherboard be the culprit if the motherboard is old, maybe a circuitry malfuction somewhere


i think it's 5+ years old so mobo circuitry going banana is surely a possibility...some times i hope to be Louis Rossmann 's son...and than i wake up still older and far less competent than him  

+ i can add that when it truns off, it turns on again after 1 second, and than off in a fraction of a sec... let's hope it' just a mobo death loop


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## eidairaman1 (Jan 28, 2020)

Clean your heatsink


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## kapone32 (Jan 28, 2020)

eidairaman1 said:


> Clean your heatsink



I swear sometimes you are reading my mind  totally agreed though.


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## eidairaman1 (Jan 28, 2020)

Heat or power


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## ciotta (Jan 29, 2020)

eidairaman1 said:


> Clean your heatsink


I did, i just forgot to write it on my trial/error list..updating


eidairaman1 said:


> Heat or power


Power > you mean PSU ? I tested with a brand new one
Heat > mmm... is possible to generate the amount of heat you suppose in a very very short time ? the problem kicks in after pressing power button in 0,3 seconds. The machine is of with no powercable since yesterday and it still turns off after 0,3...before bios post


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## Deleted member 67555 (Jan 29, 2020)

If you don't see any bloated caps on the Mobo look at the flat black caps.. They have 2 solders on the bottom and 1 on the top.. Right about the middle look for brownish spots...


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## eidairaman1 (Jan 29, 2020)

ciotta said:


> I did, i just forgot to write it on my trial/error list..updating
> 
> Power > you mean PSU ? I tested with a brand new one
> Heat > mmm... is possible to generate the amount of heat you suppose in a very very short time ? the problem kicks in after pressing power button in 0,3 seconds. The machine is of with no powercable since yesterday and it still turns off after 0,3...before bios post



Pull the motherboard out,  run on a non conductive surface with minimum parts, psu, motherboard, ram, keyboard, mouse, gpu/igp, monitor.

No drives


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## DeathtoGnomes (Jan 29, 2020)

eidairaman1 said:


> Pull the motherboard out,  run on a non conductive surface with minimum parts, psu, motherboard, ram, keyboard, mouse, gpu/igp, monitor.
> 
> No drives


Can the OP not get into the BIOS?

couple things to add while you have the system out of the case, disconnect the case front panel buttons and lights from motherboard, ensure the motherboard push buttons are not stuck "in". hold the bios button while you power on to clear CMOS.


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## eidairaman1 (Jan 29, 2020)

DeathtoGnomes said:


> Can the OP not get into the BIOS?



It turns on then turns right off.

I forgot, replace cmos battery.

Clear cmos if not done already.


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## ciotta (Feb 12, 2020)

UPDATE:
So i decided as a last call to replace thermalpaste. Off coure is was not fresh bacuse the PC has more than 4 years of hard work behind...but the problem was another:
There are 2 cables that you must plug to the Liquid CPU cooler: A and B (you can see those in attached pictures).
A goes from Cooler to motherboard USB3 header
B goes from cooler to FANS
Anyway one or both of them was not plugged correctly.  So I assume that the motherboard was turning off the moment it realized that CPU cooler was not working properly. After carefully replugging those the problem is now gone for good.

thank you guys for all your suggestions. WE did it!

PS: is there a way to update my thread with [SOLVED] on title?..i cannot edit it anymore


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## eidairaman1 (Feb 12, 2020)

Motherboard manuals should specify that


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## funboy6942 (Feb 20, 2020)

Very first thing I do when working on a pc, laptop, or video card is redo the thermal paste, and 90% of the time was the cause of the weird stuffs a going on. I change my paste every year, and thermal conductive pads every 2 years or so for you can buy new ones of them, if you didnt know. In doing this as a rule of thumb, my pc's will chug along year after year, and even more years after that when my son inherits my old hardware as I upgrade to newer stuff running my old stuff for another 4-5 years with not a single problem. And knocking on wood, doing it this way, I have yet to have to replace ANY hardware because of a failure in ANY of the systems I have built in the 20+ years I been working and building computers, for I have people bring me their stuff back every year to do a fresh reinstall of windows, and upkeep of their stuff for them.


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## Ayhamhamadeh (Oct 29, 2020)

Hey, I had same problem and wanted to mention that I also fixed it by changing the CPU-Cooler. I didn't know that without cooler the CPU will get too hot in 1 sec.... 
Anyway thank you for your updates.


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