I usually leave my computer on overnight, I just turn off my two monitors which are daisy-chained. A month ago I noticed that the Computer would turn off / restart overnight. When I turned on the monitors in the morning (the power button for the computer would be still on), the main monitor would say 'Entering power save mode', and shortly after that the Computer would restart and I would be prompted with the Windows login. In the windows log file, it would say 'unexpected shutdown'.
I tried to go through all the power settings in Windows 10, disabled sleep, disabled hibernate, update and remove drivers, googled around etc. At some point, I had followed some advice to change some registry keys but it didn't fix the problem that I had in the morning. However, one time I left the monitors ON during the night and the computer was still running normally in the morning.
I figured that once I turn off both monitors, my computer immediately had the problem above. I could turn off both monitors, and turn them on 1 seconds afterward again and my computer would restart. My computer runs several days (until the next Windows update force restart...) if I leave on the monitors (they do use screensavers, just the power remains on).
At that point, my computer had experienced so many unexpected shutdowns and registry changes that I decided to do a clean install of Windows 10 and see if that fixes the problem once and for all. It did not.
So now I am sitting here with pretty much a clean install of Windows 10 and a computer that goes to sleep/restarts whatever we want to call it once I turn off and on my two monitors. If I only turn off either one of them, all works fine, it doesn't affect the computer. If I remove the daisy-chain of my monitors and only connect the computer to either one of the monitors, everything works fine as far as I can tell! That is, turning off the monitor and turning it immediately back on again doesn't affect the computer running.
- OS: Windows 10
- CPU: i7 5930k @ 3.50 GHz
- GC: GeForce GTX 960
- Memory: 32 GB
- Monitors: Dell U2715H (main) and Dell P2416D (secondary)
Cliffnotes: My computer restarts once I turn on two daisy-chained monitors that were previously turned off.