Computer turns off randomly. Sometimes after 2 minutes of use. Other times after 2-4 hours of use.

Specs:

Motherboard: Gigabyte Z170MX Gaming 5
CPU: Intel Core i7 6700k
Graphic Card: MSI GTX1070
PSU: Evga nex650G gold standard
RAM: G.SKILL Ripjaws V Series 16GB
CPU Fan: Cryorig H7

I recently moved to Japan from the United States, and brought my desktop computer with me. When I initially assembled my computer and hooked it up in Japan, it worked perfectly fine.
I was able to play overwatch, watch videos, and browse the internet with no problem. My motherboard, PSU are brand new as I RMA'd both parts because of previous issues.

Now, my computer turns off randomly. Sometimes after 2 minutes of use, and other times after 2-4 hours of use. I've taken off both sides of the case to ensure air is properly flowing through the case, but my computer still turns off randomly

Below are the random times my computer turns off:

-Turns off suddenly right after turning on the computer while in the log in password screen
-Turns off suddenly right after logging into the computer without any applications open after 5-10 minutes
-Turns off suddenly when using google chrome, lightly browsing the internet after 20-30 mintures
-Turns off suddenly after 2-3- hours of watching videos/movies.
-Turns off suddenly after computer is idle for 1-2 hours
-Turns off in BIOS mode

Also tested my computer without the GPU installed and with only one stick of ram. Computer would turn off randomly while in BIOS mode.

I thought it might have been the PSU, but if the PSU was the problem, would the computer be able to run for 2-3 hours? Also, the PSU is pretty new so don't think it is the problem.

Checked the temperature with HWMonitor and it seems some area on my mother board "TEMPIN2" is at 102C or at some ridiculously high temperature. Looked up in various threads what "TEMPIN2" is referring to on the motherboard. Can be possibly the NB or VRM.

I've actually RMA'd the gigabyte mother board two times already. Can it be a motherboard issue again?

Thanks for your help. I've been having issues with my computer every six months or so, and is extremely frustrating, even now so because I am unable to RMA parts that I bought just last year.