PC crashing on R6 Siege / BO4

[Rubbun]

• Ryzen 5 1600 @ 3.7
• Gigabyte 1050 Ti OC +200 Core clock, +600 Memory clock
• 16gb DDR4 RAM
• AB350m mobo
• 550w Corsair PSU
• Windows 10 Professional 1803
• Games on a HDD
• 2 screens (144hz and 60hz)

Hello, new to the forum.
Lately I've been running into annoying crashes while playing R6 Siege and Black Ops 4. Out of the 3 more intensive games that I play (Quake Champions being the third one), those 2 are the ones giving me problems. Quake Champions has never crashed my PC so far, but those 2 have in numerous occasions.
This is something that started happening frequently about a month or two ago. It also happened back in January this year, but not nearly as frequent, and I could fix it by setting my fan speed to 100%. This time around, that's not helping.
Basically, after about 30 minutes (sometimes more) in game, my GPU seems to turn off. Screen goes black and the GPU fans go quiet, but all other fans (case and CPU cooler) will continue spinning. While it's been more consistent lately, it's an issue I didn't have everyday before. One thing I noticed is that my PC wouldn't crash on LAN games (R6 Terrorist Hunt solo, for example), but would on online games. I could even avoid crashing by restarting my internet, but that seems to have stopped working as well. Don't think my internet can crash my entire PC anyway.

I've been running FurMark for about 40 minutes in the background without a single crash, and with a 10min session previous to this one, so I don't really know what's going on. So far, it's seems BO4 and R6 Siege are the only apps that have been causing my PC to crash. It's driving me absolutely nuts.
I know it's not a temp issue. My CPU runs at max 65°C, and my GPU barely ever goes beyond 60°C. In fact, this is the first time I've seen it go way above 60°C. My GPU does seem to reach 99% usage on both games though, but it's not consistent.
I play those 2 games at low settings. Siege hovers around 120-140fps (capped with Rivatuner). BO4 hovers around 80-144fps in Blackout.
I've tried a few things. I've DDU'd and reinstalled the latest driver. DDU'd and installed an older driver that never gave me issues. Reseated the GPU. Played without overclocking it. Changed Windows power settings. Restarting my Internet. Completely restarting my PC from scratch and playtesting.
I just don't know what to do anymore. I don't know what's wrong or how to fix my issues.
Any help is appreciated.

 

[kastriot]

Test your gpu with unigine heaven and set tesselation parameters at max+aa@8 and leave it about 1 hour.

 

[Rubbun]

Test your gpu with unigine heaven and set tesselation parameters at max+aa@8 and leave it about 1 hour.

Will do tomorrw. I'm tired, BO4 just crashed again. Thanks for the idea.