I've got an install of arch linux on my B+, but the test pattern is showing in the upper-right corner of the screen even well after the OS is fully booted. It disappears every now and then, but comes back when I take any action. I think it is getting re-drawn whenever there is activity on the GPU. I've looked through tons of documentation on config.txt hoping to find a solution, but to no avail. Has anyone else seen this issue? Is there anyway to get rid of it?

  • Hello and welcome to Raspberry Pi.SE Is this pattern showing up on the command line or in X? – Ghanima Apr 13 '15 at 14:18
  • @goldilocks I don't think the archlinux tag is appropriate, the problem doesn't relate to arch itself and could present in any OS – smokes2345 Apr 13 '15 at 19:32
  • You're right. It wasn't actually me that added that (I just put "rainbow" in the title"), but I've removed it. You can rollback/change edits other people have made to your own question, BTW. You can see the revisions in order by clicking on the "edited ___ ago". – goldilocks Apr 13 '15 at 19:36
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    Couldn't know that by then... BTW "test pattern" is also misleading. – Ghanima Apr 13 '15 at 19:41
  • @goldilocks so sorry, i though i saw you in the edit history there, i'm cool with your edit, actually. I'm aware of how to check revisions, apparently i just didn't look closely enough. – smokes2345 Apr 13 '15 at 19:51

It sounds like one of two warnings.

  1. red square over temperature (>85 C)
  2. rainbow square power supply under voltage (<4.65V)

See http://www.raspberrypi.org/forums/viewtopic.php?f=29&t=82373 for fuller details.

  • Thanks, it's the rainbow square, I was powering it from a USB port on a sleeping/hibernating computer. I feel like this should be documented at raspberrypi.org/documentation/configuration/config-txt.md – smokes2345 Apr 13 '15 at 14:27
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    The Foundation is a little lame WRT documentation, unfortunately. I think the most exhaustive, organized source is their github site. If you click through to "documention" you can do word based searches at the top. I don't think this is anywhere there, though. – goldilocks Apr 13 '15 at 14:48
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    @goldilocks Unfortunately that appears to be true. elinux tends to be more accurate than the raspberrypi.org documentation. Perhaps because it's easier to edit on elinux. – joan Apr 13 '15 at 14:52

I get the under-voltage (rainbow) when running quite a few of the full screen pi3d demos whenever there's quite a bit going on. The cpu monitor is down less than 10% and it seems to do it with or without the x server running. The power supply is a good quality USB and I've never had any other under-voltage problems.

However you can disable it if you really want (as per @joan's link)

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