Question High Definition Power

[kerangovender]

This is what I accidentally did...I connected my pi3B+ and used it for a while for about an hour or so...then I pulled out the power cable with HDMI still connected, the system kept running as well as the 12V PC fan on the GPIO until I manually shut it down and pulled out the HDMI cable and everything turned off...

Can someone explain what I discovered or has it been done before?

 

[kanewolf]

If you look at the pinout of HDMI -- https://en.wikipedia.org/wiki/HDMI You can see that there is a 5vDC pin. The amount of supplied power is dependent on the monitor but, whatever you were plugged into, had enough to support your PI.