Question PC restarts randomly. No solution seems to be working.

Jun 24, 2019
Hi, so I have this PC with pretty old spec (parts are listed below). I've been using it for just over a year and never had any problem until recently. The problem started around 2 months ago, the computer restarted when I was playing certain game title. As time progress the problem is getting worse. So, here are the conditions I found and solutions I've tried so far,
Conditions :
  1. No bsod or warning whatsoever.
  2. Kernel Power 41 (or whatever it is) is written in system log.
  3. Restart occurs randomly. When idle or even when booting.
  4. Normal Temperature on both cpu and gpu.
  5. The system survives stress test but not AAA games.
  6. The system worked fine for a whole week after I left it for a month.
  7. The system turns on by itself from sleep. (this didn't happen on the week mentioned on number 6)
Solutions I've tried :
  1. Replacing PSU and RAM with working one
  2. Removing GPU
  3. Resetting CMOS
  4. Changing power plan and related setting.
  5. Reinstalling driver
Specs : i5 4690, GIGABYTE G1 Sniper b5, Team dark 1x8 gb (replaced with crucial ballistix 1x8gb), evga gtx 770, corsair vs550 (replaced with FSP hexa ii 500w), 120gb+1tb storage.
I suspect the cpu or motherboard as the culprit, but so far I can't find a replacement for either of those unless buying a new one. Please help, I need the computer to do my college works. any suggestions are appreciated! Thanks!