Question No signal from gpu

Jul 18, 2020

Under load my GPU turns off and the screen goes blank then "no signal", sometimes "out of range" appears but the computer itself remains on since i can hear windows sound effects, or music i just cant see anything.
What i tried:
  • removed gpu and switched to integrated graphics (intel hd 530), still the same issue, but not as frequently. It happens mostly during alt-tabbing or when applications start in fullscreen mode or when the screen resolution changes
  • completely removed and reinstalled nvidia drivers, 2 different versions
  • reseating CPU and new thermal paste
  • reseated/removed RAM
  • cleaned PC, GPU and power supply
  • DVI instead of HDMI cable
  • different monitor
  • different PCI slot for GPU
  • different PSU cable, both the 8 pin one that goes into the GPU and the large one, that goes into the wall outlet
  • bios factory settings reset
  • bios voltages are okay
  • changed fan speed to higher and lower rpm
  • updated windows
  • safe mode
What i did not try:
  • different power supply and GPU (dont have)
  • reinstalling windows 10
None of these seemed to fix my issue, my PC is not overheating, the GPU does not go above 80°C and the CPU is around 45°C under load, and the idle temps are much lower. It first happened a few weeks after reinstalling windows due to a faulty hard drive, but it never happened before. I'm mainly using AutoCAD, Blender, office applications and games when the issue happens. Sometimes the graphics card shuts off immediately when i launch a program that uses GPU, and sometimes i can run benchmarks for an hour before anything happens. I bought this PC in 2015 and only had the motherboard replaced around a year ago, to a same board, only with newer bios version. What could be the issue? I was guessing the GPU, but since it also happens with integrated graphics, could my power supply or motherboard be faulty?
  • ASRock z170m motherboard
  • Intel core i5-6600k (not overclocked)
  • GTX 960 4GB
  • 16 GB DDR4 kingston memory (2x8 GB in dual channel)
  • 750W EVGA PSU
  • 1 TB Toshiba HDD / no SSD
  • Windows 10 64bit
Thank you for reading!