Question PC randomly shuts down, refuses to power on despite mobo/gpu power led is on

[Brian Foo]

just built a new system and been using it for a few months with no issues at all, the 1st instance of the random shutdown happened early may when my pc suddenly shuts down without warning as if the power has been cut off, but mobo/gpu are still receiving power as the leds are still lit, tried powering on but the pc refuses to even power up/post. no reaction whatsoever from pressing the power button. tried
reseating components, tried powering on without gpu, ram, etc. nothing.

after that i disconnected the power cord and leave it there for couple of hours, and it boots up just fine as if nothing happened. everything was fine until a few days ago when it happened again, shuts down suddenly as it was idling, refuse to power on. waited a couple of hours and booted up fine again.

could it be the PSU failing/defective? psu caps, or some unstable rails? The psu is barely a few months old, but i did notice a very faint buzzing noise every now and then from the psu that comes & goes.

PS: didn't have a spare psu to try shortly after it happened though

system specs are:

-Asus ROG H370-F gaming
-Cooler master MWE 650W (modular) Gold
-Intel Core i5-8400 (using Thermaltake Riing Silent 12 CPU Cooler, properly mounted with provided mounts and parts, thermal paste correctly applied)
-Asus Strix GTX1060 6GB
-Kingston HyperX 8gb 2666 DDR4
-D-link DWA-582 AC1200 wifi pci-e card
-Transcend 120GB SSD
-WD blue 500GB HDD


-system stress tested with aida 64 extreme, component thermals, system stability are all good.

Any insight into this would be greatly appreciated. thanks in advance

 

[PC Tailor]

Without a spare PSU to test, I would definitely be swapping PSU with a new one, return it under warranty.
The CM MWE series (from my awareness) is a poor quality model. Budget line if I am not mistaken.

You'll then identify if it is something else, but it is very likely PSU.

 

[Brian Foo]

Without a spare PSU to test, I would definitely be swapping PSU with a new one, return it under warranty.
The CM MWE series (from my awareness) is a poor quality model. Budget line if I am not mistaken.

You'll then identify if it is something else, but it is very likely PSU.

just sent it in for warranty, hopefully the PSU is the cause, kinda worried for a bad mobo/cpu though....could they exhibit similar symptoms?

 

[PC Tailor]

They could certainly.

CPU failure is rare though so I'd be incredibly surprised if it is that.

Usually PSU is the first port of call in most cases and especially budget ones.

 

[Hep]

Being that after a length of time it seems to work again, sounds like a possible cooling issue to me. I'd monitor the temps for a bit until it happens a again.