I hope someone can help me, I've bought my first Rpi a few months ago and I haven't been able to use it at all because of this issue.

Specs: Raspberry Pi 4 - 4GB

OS: Raspberry Pi OS with desktop Fully updated with

sudo apt full-upgrade

Nothing else has been installed

This is the case and fans I'm using: enter image description here

The pi reboots constantly, sometimes it was as much as once every hour or less, now it takes around 4 hours I think.

After a lot of testing I realized the problem occurs when I select a DMT resolution (any resolution) even tho I have no HDMI connected. I do this so I can connect through VNC and can interact with the desktop.

I took the pi to the service of the place where I bought it before realizing this was the issue and they did not found any problem, when I contacted them again with my new find they said they couldn't do anything because in their initial inspection they couln't find any error.

I tried changing to the FakeKMS Driver following this answer https://raspberrypi.stackexchange.com/a/88184 but it only made the pi take a bit longer to reboot.

I looked at all the usual logs people look at to diagnose crashes (syslog, dmesg) and couldn't find anything meaningful. If it helps I can get some logs and upload them anyway.

Is this normal? Or could this be hardware related?

  • My guess would be temperature or PSU. Logg those values. And post a link to the case not just a picture.
    – MatsK
    Aug 27, 2021 at 6:43
  • When does the reboot happen? Your title says "when changing resolution", yet the question body says "once every 4 hours"? Aug 27, 2021 at 8:39
  • @MatsK It's not the temperature, it's idle, so it's not getting more than 27-32C° (depends on the day), I don't think it's the PSU, it would be weird since it works fine when I don't specify the resolution, even when doing power intensive stuff. @DmitryGrigoryev Sorry about that, I meant after changing the resolution, the random reboots start, but it's not instant. Yesterday I ran vncserver -depth 24 -geometry 1920x1080 and connected using just that without changing the resolution, but today it rebooted too. Is there any other log I can look at besides syslog and dmesg?
    – Psycoguana
    Aug 28, 2021 at 14:49

1 Answer 1


You mention no HDMI connected and using VNC ... so running headless ?

Yesterday I ran vncserver -depth 24 -geometry 1920x1080 and connected using just that without changing the resolution,

I am puzzled as to how you would be entering that command ? In a terminal window in the VNC desktop ?

Is the RasPi connected by an ethernet cable or Wi-Fi ? If Wi-Fi, that may be where your problem actually is. I have problems with Wi-Fi on my RasPi Zero randomly dropping out then reconnecting :-(

What are the messages at end of syslog and dmesg ?


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