I posted "Radeon HD 7700 Win 10 freezes when attempting to "Turn off display"" two months ago without an answer.
I now have more information and I've determined the issue is the 7750 with the Radeon driver. The system details are
Dell Optiplex 3010
A21 BIOS (latest), Bios settings to default
i7-3770, 16GB ram
Win 10 Pro 64-bit 1809, in a domain (same issue with 1803)
Samsung Pro SSD
Radeon HD 7750 (18.12.2, have used the last three versions, all have same behavior)
Dell P2414H (x2) monitors connected via displayport
Power configuration is always on. The display timeout is 15 minutes.
If no one is logged in, the displays turn off after 15 minutes and will not wake up via USB mouse or keyboard. The computer can still be
pinged. After a while it no longer responds to pings and must be powered down and restarted.
If a user is logged in the displays turn off after the timeout period. There is no issue with waking up the computer with the USB mouse or
keyboard. It works just fine.
The event log has a curious error in the system log just prior to the unexpected shutdown (via hard power off/on).
A timeout (30000 milliseconds) was reached while waiting for a transaction response from the AMD External Events Utility service
I've tried disabling the AMD External Events Utility service but that caused other issues.
And, yes, I can disable the display timeout and this issue does not occur. However, I would prefer the displays turn off to save power.
In frustration I uninstalled all AMD drivers using their clean utility. With standard Microsoft display drivers, the computer works fine (albeit with
duplicated displays) and the displays turn back on via USB mouse and/or keyboard whether or not a user is logged in or not.
That tells me there is some interaction between the 7750 and at least the last few revisions of the driver, perhaps tied to display port and/or
dual monitors. Perhaps there is some vital software that only runs when a user logs on that is not present when no one is logged in?
This is very frustrating because the user must remember to not log out, which is against company policy, but is required if they need
to login remotely. I have and HD 7800 and R9 380 as well as lesser radeon cards and do not have this problem.