Pi4 GPU failure?

A strange thing happened yesterday: working away on my RO Pi4, the screen started to blank intermittently; the desktop would return after a few seconds, then blank and return again with increasing frequency, finally, after about a couple of minutes, blanking and NOT returning to the desktop. Several hours’ rest and the machine seemed back to normal but failed again this morning, and I have replaced it for the time being with its predecessor, a Pi3B. As this is displaying normally, and as a Wintel laptop on a KVM switch also continued to display normally throughout, I’m exonerating the monitor.

I suspect GPU failure, or possibly the power supply. The Pi4 is a little over 3 years old and has been intensively used during that time, mostly at normal clock rates but latterly at 1800 and 2000Mhz (temps in the latter cases didn’t exceed 65 deg. C however). I was wondering if anyone else has had a similar experience?

HDMI lead to the switch?

My guess would be a dodgy micro HDMI cable, as I had pretty much the same thing with one of mine. Of course if you switched to the Pi 3B you will be using a full size cable so you wont see the problem. Try the Pi 4B again and wiggle the cable.

My guess would be a dodgy micro USB cable, as I had pretty much the same thing with one of mine. Of course if you switched to the Pi 3B you will be using a full size cable so you wont see the problem.

I’m guessing “microHDMI” and not “microUSB”? Because otherwise it does not make sense.

Just to take the opportunity to moan again about that braindead RPi Foundation decision to go for microHDMI sockets. It’s a headache. And not to forget that it was miniHDMI for the Pi Zero. I strongly recommend using one of the many cases now available that convert microHDMI to full-size HDMI (DeskPi, ArgonOne) and never ever invest money in microHDMI cabling. Or adapters (which never worked for me, and they put a lot of strain on the sockets).

Try the Pi4B again and wiggle the cable

Did that. Same result, basically: at first it worked, then it didn’t. So I’ve retired the 4B for the time being, the trusty 3B is taking up the slack (and seems to run !Iris from RAM fairly well – once I’d upgraded the ROM to 5.29 – which was a surprise. It doesn’t feel all that slow either, which is also a surprise). On the basis you look for the cheaper cure first, I’ll try a new MicroHDMI cable. If that doesn’t work, maybe it’s time for a new Pi. Those Zero-based models with eMMC look tasty (familiar voice rings in the mind’s ear: “Not another one of those weird computers of yours….!”).

How dead is it when it fails to blank screen? Can you reinsert the microHDMI cable and get back to a viable desktop? Mine is in a case so am just using standard HDMI fine.

Can you reinsert the microHDMI cable and get back to a viable desktop?

That hasn’t worked, but the Pi keeps responding to keyboard input apart from the blank display and the SCSI SSD hard drive light continues to flash. Ctrl-Break reboots as normal. Sound seems normally functional also. So my guess is the problem is confined to the video circuitry.
CASE: Steffen mentioned using a case above, and interesting that Stuart does also. I’ve always mounted my Pi’s alfresco on a monitor-back VESA mount; maybe I should look at a case.

Oops MicroHDMI. You could try putting Linux on the Pi 4B and connect the monitor to the second HDMI socket (Linux works with either or both). If you get the same issue it’s likely to be the chip at fault, if not it may be the first HDMI socket has a dodgy connection, which might be fixable. Is the Pi 4B still under warranty?

Using VNCSrvr would enable you to connect to the RPi4 from another, and it may show the RPi4 is still working (or not!) when its own display fails.

I had a similar problem with a pi3.
A few times a week the screen would blank randomly and sometime just stayed blank and only a power of reset would get it working again.
I set up VNC on it and that showed that when the screen went blank, and stayed blank, I could vnc into it and according to the computer everything was fine.
I changed the monitor and the HDMI lead but still had the same problem, but after changing the power supply the problem went away.

I have a similar problem with my Pi400, the stock hdmi lead has a large very rigid connector at the pi end and that has cracked the socket off the mother board to some degree. A slight wriggle of the leads has restored video every time so far. I am not looking forward to actually having to deal with this so long may it say a it is.

Thanks to everyone for the feedback and the suggested remedies/work-arounds. I’ll work my way through these over the next few days – I have a Debian-formatted SD card for the Pi, so David’s tip about trying it in conjunction with the 2nd HDMI socket should be straightforward and I’ll try that first. I’ll post results here.

You try putting Linux on the Pi 4B and connect the monitor to the second HDMI socket (Linux works with either or both).

Last year after giving a demonstration at a friend’s house I plugged it back on the second socket when I brought it home and it worked but without sound. Note that on Raspbian, when you use the second socket you need to select the correct output or will continue to try to send sound to the first HDMI socket, so I think RISC OS just lacks a little piece of code to do the same.