Question [FIXED] PC random blackouts

[akashtaker001]

I have a very peculiar problem. My PC turns on normally and works great for a while. But randomly shuts down.
The monitor turns blank.
All the cabinet fans, CPU fan and GPU fans keep spinning.
My Keyboard's backlit is also on, but for a few moments my Num Lock key is responsive but after a few moments I can't change the status of my NumLock.
Now only way to turn on PC is by Pressing Power Button for a few seconds after that System turns off and it turns on normally. But the cycle is still repeating.
I have tried replacing my RAM to no avail.

My specs are:-
AMD Ryzen 1700
Asus Prime X370-Pro Motherboard
Sapphire AMD HD7950 GPU
8GBx2 DDR4 RAM
Corsair GX750 power supply
OS- Windows 10 Pro 64 bit and Manjaro Gnome 64 Bit

 

[PC Tailor]

What Corsair power supply exactly is it?
Does the issue still occur in safe mode?
Does the display just go blank until you hard reset it?

 

[akashtaker001]

What Corsair power supply exactly is it?
Does the issue still occur in safe mode?
Does the display just go blank until you hard reset it?

Power Supply is GX750
Yes issue occurs in Safe Mode as well as Manjaro Linux I have in dual boot.
Yes Display is blank untill I hard reset.
My Keyboard's NumLock is responsive for a few seconds after blackout. But it freezes after that. Although Keyboard's backlit stays on.

 

[akashtaker001]

My problem has been solved. If anyone else is facing a similar problem. Here is what I did.
I opened my GPU heatsink, and saw that thermal compound was powdery and cracked. I cleaned it with rubbing alcohol and replaced it with a thermal paste I had lying around. Also I thoroughly cleaned the heatsink with a blower. Now everything is working fine.