I recently upgrade my gpu from a GTX 780 to RX 580, now every time i boot Windows 10 appears a second screen as non-pnp generic on Microsoft Basic Display Driver.
I tried reinstalling Windows 10, gpu drivers using DDU and restoring BIOS to default but nothing helped.
My motherboard is a MSI Z77 Mpower whit i7-3770K as cpu, in the BIOS i have disable integrated graphics.
The only thing that helped is rebooting PC after power on but it is tedious.
Tried this even with command line and there is no difference at what shows up in device manager under monitors and graphics cards between if i just seleced "show hidden devices" without touching the variable. Microsoft documentation states that from Windows 8 and later there is not need for this command line option as the "show hidden devices" has the same effect (https://support.microsoft.com/en-us/help/315539/device-manager-does-not-display-devices-that-are-not...).
My system is not even a year old and i see no reason why a dead CMOS battery would cause the issue. The BIOS time ould reset if the battery was dead, which it isn't.
Avout Fast Startup in Windows 10 - as you article pointa out reboots are not affected by fast startup at all. I never shutdown anyway - only restarts.
I'm not suggesting the CMOS battery is dead. The computer stores some settings, like hardware, in the CMOS, Removing the CMOS battery for a minute or two clears these settings which may have been corrupted. Replacing it refreshes the storage with current (hopefully correct) settings.
From what I found it seems to be a combination of Intel HD Display Drivers or Hyper-V installed. These were on Laptops but might be the same for Desktops with Intel APU/CPU or Graphics installed.
I googled "Non-existent Monitor" and found several links.
According to this link from Spicework, Hyper-V is the reason for Non-Existent Monitors to show up: [SOLVED] Windows 10 detects too many monitors, does not display on actual monitors - Spiceworks
This may have helped the original poster even without the Hyper-V portion as after a short time of googling one will find there was indeed a problematic intel graphics driver. Hence kofus has marked your reply as helpful. Kofus, has this been indeed been reaolved by elstaci's answer?
However, kofus has an integrated GPU in his Intel CPU. I have a Ryzen 1700X which means this is not relevere to me. Incidentally i do not have Hyper-V installed butdid uninstall VMware Workstation a few days ago to try to reaolve the issue.