Unexpected shutdown

Hello,
This is my first post, because I find myself in an unusual situation. Until now I have always solved my problems with my different mono-boards, by finding the solutions on the forums. But the I dry.
I have since maybe two Rock 5 (4Go and 8Go), tested with different power supplies (9v/3a and 12v/3a), and different images (Debian 11, Ubuntu server, Armbian), updated (on SD or EMMC), and the two cards stop unexpectedly, after launching the system, without being overloaded, sometimes after several minutes, sometimes just after the login.

I specify that my cards have a fan, which I do not see working. I even tried turning my cards on with the fan disconnected, but that didn’t change anything.

Thanks for your help.

Sincerely Marc.

PS: With Armbian after choosing my locale, the screen turns black and the message “hpptx phy p11 locked! hpptx phy lane locked! …”

Hello,
I think I have found the source of my problem.
Last night with my Rock 5B 8G, I was able to update my Ubuntu version on SD,
which took a while, but I didn’t experience any outages.
I continued with a video player on Youtube from 9:40 without problem.

So I think I must have an electrical problem, which I didn’t have with my old boards
(Tinker Board) or even my Rock 4.

Sincerely Marc.