Which is DEAD my MOTHERBOARD or faulty PSU??

[seoparkeu]

I am working with designs stuff (graphic designer) I have this hectic schedule and a dead end in which will really end in December... So here's my problem ... My System unit keeps powers on and off without any prompt that will happen after 30 mins (not really defined set of an integer sometimes for 20 mins it will stay then shuts itself ) so I keep waiting and waiting until the problem suddenly stops ... but after 2 days it occurs again which is worse at this time even in the POST it shutdowns ...

So here's what I have done (Diagnose)
-> I remove the GPU ... power on the pc then same problem (maybe not the GPU?)
-> Reset my BIOS and change the 2032 battery ... power on the same problem (not the software?)
-> Change the RAM slot I have 4 slots (8gb) with each one same problem occurs
-> Ran the PSU with itself only (paper clip mode) for 6 hrs to see whether it is running
-> The Last thing is that I ran the PC with the minimal power outage ( I mean no GPU )
-> Out for desperation I spray the whole system with Mr. McKenic Contact cleaner.

So I think the problem is maybe the MOTHERBOARD I mean I bought a cheap motherboard back then.. is it my motherboard that I have to replace or the whole entirety of this system unit.

And last thing, I dont really shutdown my pc I just use the sleep mode is it any good?

System Unit specs:
Motherboard: MSI B75a-g43 gaming [ Temps Ave | Idle: 28-29 | Adobe: Max 32 ]
CPU: Intel i3 3220 [ Temps Ave | Idle: 41 | Browsing : 41-45 | Adobe : 46-51 | CAD, Maya: 53]
CPU Cooler: Seidon 120v plus
Thermal Paste: Generic 1.2W/m-k
Graphics Card: Nvidia Quadro P5000
Ram: Kingston 8gb 1333mhz
PSU: Cooler Master GX Bronze 650W
SSD: Crucial MX100 512GB

 

[ChumP]

From your troubleshooting process it really sounds like that motherboard is the issue.
Had a simillar problem with an old LGA775 motherboard that would shut down at arround the 10 minute mark constantly.
Using sleep mode instead of shut down shouldn't be a problem