Computer turning off

[Elyxium]

I've had my computer for about 2-3 years now, it's a custom built I bought off a website. I believe it was cyberpower or something related but it's ran fine up until the 1st year of having it. It turns off when I play a mmorpg/moba game. Sometimes it turns off randomly, not all the case fans function properly but I have a program monitoring heat and it doesn't look like it overheats before it turns off. I can't figure out where the source of the problem is coming from. I've asked for advice from several other people, their solutions have lead to me to replace my PSU with an 850W gold, I replaced my hard drive, cleaned out all the fans with computer duster.
After I replaced the hard drive the issue stopped for about 1-2 months, same with after I replaced the PSU (both at different times)
I just don't have the money to take it to a professional to get it looked at right now so I was hoping someone might have some more definitive ideas!
It's a clean install of windows 10, no viruses as far as my virus protection can detect, I use mal-ware/spyware programs as well.

My build is
Processor - AMD FX(tm)-8350 Eight core processor
Hard drive - 1TB hard drive
PSU - 850W gold EVGA fully modular
Motherboard - Asus Sabertooth 990FX (not sure which one! I think it's the cheaper of the 2)
I forgot which graphics card I had put in! I believe it's a Radeon ICEQ not sure which model sorry!
I think that's everything

Please let me hear any thoughts!
Thanks for reading, your time.

 

[Cycloid Torus]

"not all the case fans function properly" - wondering if malfunction of fan (like a short) might be source of problem.

Does it freeze (program still there just halted) or crash (program gone) or does it just glunk up with sound still playing?

Any messages or beeps?

What are the special characteristics of "turning off"? Sounds? Sudden speed up of fans? Anything?

Turn off 'restart on error" in BIOS.