HP EliteDesk 800 G4 DM running Home Assistant OS randomly hard-reboots when headless – DisplayPort dummy plug fixed it
I want to document this issue in case it helps someone else running Home Assistant OS on an HP EliteDesk 800 G4 DM.
Hardware
- HP EliteDesk 800 G4 DM 65W
- Intel Core i5-8500
- Intel UHD Graphics 630
- Home Assistant OS Generic x86-64
- NVMe: SK hynix BC511
- BIOS family: Q21
- current BIOS: Q21 02.33.00
Symptoms
The EliteDesk was running as a headless Home Assistant server without a monitor attached.
It experienced frequent random full system reboots.
These were not normal Home Assistant Core restarts. The Supervisor, all add-ons and Home Assistant disappeared at the same time and subsequently started again.
After one of these reboots, Home Assistant reported:
The system could not validate that the sqlite3 database
was shutdown cleanly
Ended unfinished session
So Home Assistant had clearly not shut down normally. home-assistant_2026-08-29T14-43…
HAOS also reported after crashes:
Dirty bit is set.
Fs was not properly unmounted and some data may be corrupt.
hassos-data: recovering journal
However, the host logs before the crashes showed no obvious reason for the reboot.
I specifically searched for:
kernel panic
OOM / Out of memory
Killed process
soft lockup
hard lockup
hung task
NVMe timeout
I/O error
EXT4 error
thermal shutdown
segfault
normal shutdown
normal reboot
None of these appeared before the crashes.
The journal simply stopped after otherwise normal messages.
Troubleshooting performed
I tried the following:
- replaced the RAM completely
- updated BIOS from Q21 02.27.00 to Q21 02.33.00
- tested another genuine HP 90W power supply
- inspected host logs from multiple boots
- searched for NVMe, EXT4, OOM, watchdog and thermal errors
- reviewed the Home Assistant Core logs
None of these solved the issue.
The important test
I then connected a real monitor to one of the DisplayPort outputs.
The system immediately became stable.
After confirming this, I removed the monitor and installed a DisplayPort EDID dummy plug instead.
The EliteDesk has now remained stable with the dummy plug installed and the previous random hard reboots have stopped.
Conclusion
On my HP EliteDesk 800 G4 DM, the problem appears to be related to headless operation of the Intel UHD 630 / Intel iGPU display power management when no display is detected.
A DisplayPort EDID dummy plug, which makes the GPU believe that a monitor is connected, completely resolved the issue on my system.
Important: I have not tested the kernel parameter:
i915.enable_dc=0
So I cannot confirm that this parameter fixes the issue on my machine.
The workaround I have actually tested and confirmed is:
DisplayPort EDID dummy plug
If you are running Home Assistant OS headless on an HP EliteDesk 800 G4 DM and are seeing unexplained hard reboots with no useful kernel errors, I would strongly suggest testing with a real monitor or DisplayPort dummy plug before replacing RAM, SSD, PSU or the motherboard.