EDIT: My displays continue to operate without issues after changing 'Video Memory Size' (configured in BIOS) from 64MB to 512MB (max available). This is consistent with the recommendation
here which suggests setting total amount of DVMT to max. The HP EliteDesk 800 G4 Mini BIOS does not permit configuration of 'DVMT Pre-Allocated.' It appears that I had configured video memory incorrectly in BIOS. I will continue to monitor this in my system.
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I have increased my BIOS 'Video Memory Size' configuration from 64MB to 512MB for the reasons stated below. I am still testing and have not determined that this change is necessary.
Details:
I am still trying to determine the cause of the display problems I stated
here and have not made a final determination. These problems are so rare and infrequent that they're hard for me to test. I am currently running without 'pipes' and without 'dummy con3' in my CLOVER config.plist (properties that I had previously guessed were needed to fix the display problems). I have increased 'Video Memory Size' in BIOS from 64MB to 512MB. After making this BIOS configuration change, I have not observed any of the problems reported
here through multiple days of regular operation. I will continue to monitor this and have still not made any final conclusions.