I've noticed that I don't get any HDMI output to a monitor if I connect the HDMI cable to the Pi after I plug in the power supply, because I have two RPis for one monitor -- one running Raspbmc, the other running RetroPie. Does anyone else have this problem / is this normal? If it is normal, why? And if not, what am I doing wrong with my setup?

2 Answers 2


Open /boot/config.txt and apply this settings:

  • hdmi_force_hotplug=1 to force hot plugin of your screen,
  • increase config_hdmi_boost to boost the signal. Lower values are meant to be for short HDMI cables, larger for longer ones. But this can also apply for (older) HDMI displays, whose HDMI receivers are not sensitive enough, irrespective of cable length.

You can find more info here: elinux.org.

  • 3
    For good measure, also add hdmi_drive=2 to make sure audio is working too.
    – Gerben
    Oct 29, 2013 at 16:12

you're doing everything right, CEC negotiations happen once during the boot process, and this is the only time your TV could be properly detected. this is perfectly normal and most Pi's work the same way.

you may get some success trying to detect your TV later using "cec-client", however I did not try this myself and could not confirm nor deny the possibility.

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