Had some issues on the same day KB4579311 was installed. It was super early in the morning and the first day after the update was installed. Not sure if causation, just very coincidental on a thoroughly stable system that hasn't changed ever.
- Kept getting a variety of BSODs while accessing some online lecture recordings. I then reset my GPU back to stock (undervolted with Afterburner) and restarted.
- Didn't help, BSODs continued and there were a whole smorgasbord of them. After a few restarts, decided to restart to check some stuff in BIOS.
- Restarted, and refused to boot to Windows (black screen after POST). Had to power off the system by holding the power button.
- System now repeatedly refused to post, repeatedly turning itself off then on again before reaching POST, or stuck at/right before POST completion.
- Had to unplug, open it up and clear CMOS.
- Went back into BIOS and took a couple of minutes setting up everything (DRAM subtimings, voltages, fan curves) back to exactly what they were before.
- Back into Windows with no issues.
- No problems in chkdsk /F and sfc.
No problems now. Everything is protected by a UPS and I haven't changed anything lately, so I can't think of any other reasons why.