Ubuntu 26.04 + AMD Radeon Vega 11 on HP EliteDesk 705 G5 — black screen/amdgpu errors fixed by BIOS setting
I wanted to document a solution that took me quite a while to find, in case it helps someone else.
I have an HP EliteDesk 705 G5 SFF with integrated AMD Radeon Vega 11 / Picasso / Raven 2 graphics.
Symptoms
Ubuntu would sometimes:
- boot to a black screen
- start only with
nomodeset
- fall back to low-resolution/software graphics
- fail to initialize the AMDGPU driver
The kernel logs included errors such as:
amdgpu ... probe with driver amdgpu failed with error -22
and AMD PSP/GFX initialization errors.
The same computer also had an intermittent Radeon driver problem in Windows 11, which initially made me suspect a hardware problem.
Hardware tests
I tested the system with:
- MemTest86 — 0 errors
- HP Processor diagnostic — passed
- HP Memory diagnostic — passed
- HP Storage diagnostic — passed
- HP System Board diagnostic — passed
The fix
The breakthrough was in the HP BIOS/UEFI settings.
I found:
Legacy Support → Enabled
I changed it to:
Legacy Support → Disabled
I left Secure Boot disabled.
After changing this setting and booting Ubuntu normally, I no longer needed nomodeset.
The AMDGPU driver initialized correctly and Ubuntu recognized the graphics as:
AMD Picasso / Raven 2 / Radeon Vega series
The system was able to run at 3840 × 2160 @ 60 Hz.
Hardware
HP EliteDesk 705 G5 SFF
AMD Radeon Vega 11 / Picasso / Raven 2
PCI ID: 1002:15D8
Ubuntu 26.04
DisplayPort
If you have this HP system and are seeing black screens, nomodeset, low resolution, or AMDGPU initialization errors, it may be worth checking the BIOS Legacy Support setting before assuming the Radeon hardware has failed.
This was the setting that solved the problem on my system.