Random reboot when idling!

[smartedpanda]

• My mid-2014 build has been running fine since June. Now it intermittently reboots these last two weeks.
• I accidently plugged my USB into my ethernet and shorted something - June 2020. I also pulled the power supply cord (the 3 prongs) and plugged it into my UPS and another short happened - July 2020. 
• It hard crashes with no BSOD, and reboots, and mainly when idle BUT it's been intermittent, but so far not under heavy load like gaming. 
• Tried - reset OC, and CMOS 
• Changed out Power Supplies Seasonic 750W to an old Enermax 1000w, still happening 
• Been on Bios F8 for 3-4 years (F10 is the newest)

Hardware Specs: 

• Windows 10 - 64 bit - 20H2 
  • Intel 4790k @ 4.8Ghz at 1.34Ghz (I've reset OC and Bios and CMOS) 
  • Gigabyte Z97Z-UD5 rev 1.2 - bios F8
  • 32GB HyperX DDR3 1600Hz (4 Dimms) 
  • Hecka hard drives - primary OS - Samsung 860 SSD
  • Enermax 1000W Power Supply
  • EVGA 2070 (reset OC)
  • Drives are updated 

Any tips or suggestions to have this hold until 2021? Can't find a new motherboard anywhere.