PC turns on & then off immediately

omega44-xt

omega44-xt

Gear up ...
So my friend's PC is turning on & within a second of button push turns off. The mobo RGB LED does light up when PSU is turned on, but when you press the power on button, fans start running but within a second everything turns back off. If you again press the power button, same happens for 2 more times before it stops turning on, all this while the mobo RGB is on. Then turning off the PSU for 5 sec resets everything.

Stuff tried:
  • Check with single RAM
  • Reseating GPU along with its cables
  • Reseating CMOS battery
  • Reinserting 24 pin power cable
  • Pushing in cables present in PSU
  • Not power button issue as I have tried booting by shorting the power button pins
Video: 20210211_154022.mp4
PC issue.mp4

Specs:
CPU - R7 3700X with stock cooler, repasted once
GPU - Inno3D RTX 2070S
RAM - 2x 8GB DDR4 3600MHz XPG D60
PSU - CM MWE 750W Gold
Cabinet - CM MB520
HDD - 1TB
SSD - Crucial BX500 480GB (OS)
SSD2 - Intel 660p 1TB

Any suggestions as to what could be the issue would be helpful. Anything else that I need to check.
I think it might be the PSU, but how to make sure?

20210211_153725.jpg

20210211_155301.jpg
 
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patkim

patkim

Cyborg Agent
Generally this behavior is a possible symptom of possible short somewhere, in PSU or on Mobo or bad CPU or any other peripheral part . I have in last few years experienced similar behavior once due to bad mobo and once due to bad CPU. Statistically CPUs rarely go bad but it's still not 0%. They do fail sometimes.

One way to test is to remove the CPU and start the system, if it sustains then may be CPU is bad. System may just continiously power on without CPU but would do nothing except spinning fans.

A short means overcurrent and with OCP in place in ATX PSUs, it might be entering the standby state. Do you need to flip the mains switch thereafter to reset the system or does it start and stop while PSU is still in standby state?
In theory you can try Paperclip test on PSU. If it fails PSU is bad, if it runs PSU may or may not be bad!

Another textbook approach is to start with minimal components and then start adding each one by one and see if it fails right in the beginning or after adding a specific part.
 
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OP
omega44-xt

omega44-xt

Gear up ...
Solved the issue, maybe CMOS was at fault.

After knowing that PSU isn't at fault, I started removing parts one by one, first GPU, then NVMe SSD, then removed CMOS battery & discharged remaining power from components, whatever its called, by holding power button for 10s w/o CMOS battery. After this, the PC started normally for the first time. Added back all components with CMOS being installed at the end & still the PC works.
 
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TheSloth

TheSloth

The Slowest One
omega44-xt said:
I turned on PSU & then started the PC. I didn't use the button on cabinet, instead shorted its terminals present on mobo. Did it just to make sure cabinet's button or the wire isn't faulty.
Click to expand...
What are you using to short the terminals on mobo?
 
Desmond

Desmond

Destroy Erase Improve
Staff member
Admin
Does the PC boot when you remove the GPU? It seems like the PSU might not be able to take the load. Either that or CPU might be overheating, motherboards will shutdown the system if the temperature crosses 90+ degrees, if the heatsink is not placed correctly, this could happen almost immediately.
 
OP
omega44-xt

omega44-xt

Gear up ...
Desmond David said:
Does the PC boot when you remove the GPU? It seems like the PSU might not be able to take the load. Either that or CPU might be overheating, motherboards will shutdown the system if the temperature crosses 90+ degrees, if the heatsink is not placed correctly, this could happen almost immediately.
Click to expand...
This
omega44-xt said:
Solved the issue, maybe CMOS was at fault.

After knowing that PSU isn't at fault, I started removing parts one by one, first GPU, then NVMe SSD, then removed CMOS battery & discharged remaining power from components, whatever its called, by holding power button for 10s w/o CMOS battery. After this, the PC started normally for the first time. Added back all components with CMOS being installed at the end & still the PC works.
Click to expand...

That PSU might even take the load of an RTX 3080, 2070S should be easy.
 
Desmond

Desmond

Destroy Erase Improve
Staff member
Admin
When I had last experienced boot issue because of RAM, it was because if a bent pin on the CPU socket, which I think was supposed to connect to the RAM controller on the CPU.

Because of this the PC would not boot if it you put RAM in certain slots.

Had to manually unbend the pin to get the PC to boot.
 
Nerevarine

Nerevarine

Incarnate
Desmond David said:
When I had last experienced boot issue because of RAM, it was because if a bent pin on the CPU socket, which I think was supposed to connect to the RAM controller on the CPU.

Because of this the PC would not boot if it you put RAM in certain slots.

Had to manually unbend the pin to get the PC to boot.
Click to expand...
This gives me nightmares
 
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