Question Gigabyte Motherboard Issue

Oct 19, 2018
I have recently brought back to life my Gigabyte PC back from the dead and I’ve been updating the BIOS and every time I seem to make a change, update the BIOS or anything that includes going into the BIOS my machine seems to just shut down and restart again which at this point it boots fine? It’s technically not causing any harm I’m just wondering why it would happen, there’s no issues with my Motherboard or any incompatibilities, machine runs absolutely fine once booted into Windows? Could this maybe a setting?
May 4, 2019
I have a gigabyte motherboard running windows 7 and all of a sudden out of no where it restarts and then boots back into Windows. Now, with that being said I have:

Checked system temperatures
Re-seated heat sync and re-applied thermal paste on the cpu
Checked for shorts and that everything is connected.
Fans are running fine
Hard drive has no errors and or bad sectors
Graphics card doesn't have any issues
Tested two power supplies-both working
There are no damages to the motherboard

I just can't figure out what's wrong with this motherboard. Is the bios corrupt?
I noticed the gpu under the gigabyte heat sync get really HOT
Boots past bios and into Windows for about 10-15 minutes then restarts and continually re-starts over and over. Until eventually I get a windows error and the computer must re-store itself. It's a real @#$% at this point but I am being patient and I know there's an answer to this madness. ANYONE. Please help!
I am at this point assuming it's a hardware issue due to overheating BUT where?
I am used to fixing overheating ylod/rlod issues on the ps3 and I'm a master at troubleshooting cpu/gpu problems but this one is a !@#$%^ mystery!!!!

Any help would be GREATLY appreciated at this point and It just might save the rest of the hair on my head!