Jan-Lukas Else

Thoughts of an IT expert

Published on in 💬 Micro
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Short link: https://b.jlel.se/s/72b
AI generated summary: I noticed my home server's power consumption dropped from 13 to 7 watts, likely due to the CPU staying at its most power-efficient state (C7) 85% of the time. Disconnecting a powered-off TV connected via an HDMI cable to the server's DisplayPort adapter reduced power consumption, possibly due to the integrated GPU.

I can’t really explain why this is happening, but I noticed that my home server is now idling at 7 watts instead of 13 watts as before. I checked powertop, and it seems that the CPU is staying at C7 (pc7) for about 85% of the time, which seems to be the most power efficient state.

Maybe it’s a result of moving my Baïkal instance to my VPS or some other updates? Maybe Home Assistant or Tailscale? The operating system is still Ubuntu 22.04. What else could explain almost 50 percent power reduction without any hardware or major software changes?

Update: I found a likely source: When the powered-off TV is connected with an HDMI cable to the DisplayPort adapter plugged-in into the home server, it idles at about 13 watts. When I remove the HDMI cable from the DP adapter, it goes back to 7 watts. So it might have to do something with the integrated GPU. I guess, I will leave the TV disconnected unless I really need it.

Jan-Lukas Else
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