I have a Pi in our elevator suite that is intermittently not booting properly. While I look at the raspberry pi (powered by a TP-LINK POE splitter, we use them extensively for Pis) the red power light dips and peaks in intensity when the HDMI line is plugged in. If the HDMI line is not plugged in, the unit appears to boot normally (activity light blinks as if the OS is loading.)

I'm not sure if there are any hdmi-related tweaks beyond the standard mode settings in /boot/config.txt, but has anyone run into this and if so, could you explain what you did to work around the issue?

  • I have run into this problem and it turns out that it wasn't getting enough power. I ended up using a wall socket usb power cable, no splitter.
    – Kyle
    Jun 30 '14 at 22:15

Looks like you Rpi is not getting enough power when connected to HDMI. Use a separate charger to see if it works. You may also need to specify a custom HDMI mode in config.txt if projector is configured at custom modes.

Hope it helps.


You probably know by now that it's a power issue. We also use POE splitters and indeed they work fine. Perhaps your adaptor isn't strong enough or there's too much loss through the cabling.

We have good results with Ubuquity POE adaptors but they run on 24 and 48v which we counter by placing a buck convertor between the wiring at the Pi end (so not at the splitter end).

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.