Are my MoBo or PSU dying?

[Avcoor]

Hi!

Specs:

• CPU

  Intel i7 4770

• Motherboard

  Gigabyte H87-HD3

• RAM

  Corsair Vengeance 8GB 1600MHz

• GPU

  EVGA GTX970 SC

• Case

  CoolerMaster Elite 334u

• Storage

  Seagate Barracuda 1TB; Kingston V300 120GB

• PSU

  Corsair TX550M

• Cooling

  CoolerMaster Hyper T4

• Operating System

  Windows 10 Pro

Yesterday I used my PC without any problems but today morning when I tried to turn it on, the Power LED simply flashed and the fans quickly spinned but stopped almost immediately and gave no other life signal if I pressed the power button. For it to do the same thing again I had to pull the plug off the wall and wait for around a minute.

I got a friend's PSU(Corsair GS600) hooked it to my Mobo, HDD, SSD and GPU and the PC turned on for around 20 minutes and then shutdown again. When I tried turning it on again it went just after the Windows 10 login screen and shutdown again.

Now a few hours later I put my PSU back again and the PC turned on and is going on for about 30 minutes now.

CPU temps were/are fine, never crossed 80ºC

What should I do to pinpoint the issue?

UPDATE:

After this post it went on for about 40 minutes and then shutted down. If I turn the PSU switch off and wait a little, the power led flashes and the fans spins and stops.

[Avcoor]

Sorry about the bump, but I haven't find the solution yet.


UPDATE:
Today my PC turned on normally and is on for more than 7 hours straight.

 

I live near the sea and in a very windy city, so sea spray is a big concern around here. I have already lost a MoBo due to oxidation a long time ago. My case has a lost of rust and there are some weird white spots inside it that I read somewhere that is sea salt that got there and the water evaporated but no visible parts of any PCB has them. Every screw inside and outside the case is rusting, even the one that holds the CPU holding latch. 

We're in a very humid and rainy season now, so my hypothesis is that the humidity in the air is condensing around some of these salt spots behind the MoBo, causing it to short and turn off.

What do you think of it?

[iamdarkyoshi]

Sorry about the bump, but I haven't find the solution yet.

UPDATE:

Today my PC turned on normally and is on for more than 7 hours straight.

 

I live near the sea and in a very windy city, so sea spray is a big concern around here. I have already lost a MoBo due to oxidation a long time ago. My case has a lost of rust and there are some weird white spots inside it that I read somewhere that is sea salt that got there and the water evaporated but no visible parts of any PCB has them. Every screw inside and outside the case is rusting, even the one that holds the CPU holding latch. 

We're in a very humid and rainy season now, so my hypothesis is that the humidity in the air is condensing around some of these salt spots behind the MoBo, causing it to short and turn off.

What do you think of it?

Ho boy. I would take the board out and examine it for corrosion. Look for blue spots.