Hi everyone,
I’m currently testing a custom OS we’re developing (called CUBE OS) on a Raspberry Pi 4B (8GB RAM).
Everything seems to start fine — I can see the initial boot sequence on the screen. But after a few seconds, the HDMI output turns into a strange rainbow-like gradient pattern
Photo of the issue:
Setup details:
Raspberry Pi 4B (8GB)
Booting from USB SSD (also tried microSD, same result)
Official Raspberry Pi power supply
HDMI connected to a 1080p monitor (tried two different cables and monitors)
Things I've tried:
Using HDMI port 0 and 1
Forcing HDMI safe mode in config.txt
Limiting resolution with hdmi_group and hdmi_mode
Swapping displays, cables, and power supply
Still no luck — the display always ends up in this corrupted-looking state after a few seconds.
Has anyone encountered a similar issue with custom OS builds on Pi 4?
Any ideas on what might be causing this — GPU memory allocation, firmware, timing issues?
Really appreciate any pointers!
Thanks in advance ！
I’m currently testing a custom OS we’re developing (called CUBE OS) on a Raspberry Pi 4B (8GB RAM).
Everything seems to start fine — I can see the initial boot sequence on the screen. But after a few seconds, the HDMI output turns into a strange rainbow-like gradient pattern
Photo of the issue:
Setup details:
Raspberry Pi 4B (8GB)
Booting from USB SSD (also tried microSD, same result)
Official Raspberry Pi power supply
HDMI connected to a 1080p monitor (tried two different cables and monitors)
Things I've tried:
Using HDMI port 0 and 1
Forcing HDMI safe mode in config.txt
Limiting resolution with hdmi_group and hdmi_mode
Swapping displays, cables, and power supply
Still no luck — the display always ends up in this corrupted-looking state after a few seconds.
Has anyone encountered a similar issue with custom OS builds on Pi 4?
Any ideas on what might be causing this — GPU memory allocation, firmware, timing issues?
Really appreciate any pointers!
Thanks in advance ！
Statistics: Posted by Redhorse2 — Thu Jun 26, 2025 9:28 am