I can't speak to if it's more or less efficient, but I have one PC taking backups that's running at 43W idle. A different PC based server, which is a much more highly specced retired desktop, is running at 72W idle.
For standard PC's (ie with ATX based power supply) the 43W one seems pretty decent at idle.
The small form factor gear though can have much more efficient power supplies, so some of those reportedly idle as low as 6w. That's total power draw at the wall. Much more efficient than a standard desktop PC.
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That aside, apparently that newer 12 volt power supply standard being pushed by Intel is good for lower power idle too. Hopefully that gains traction and reduces everyone's power bills. :)
The small form factor gear though can have much more efficient power supplies, so some of those reportedly idle as low as 6w. That's total power draw at the wall. Much more efficient than a standard desktop PC.
---
That aside, apparently that newer 12 volt power supply standard being pushed by Intel is good for lower power idle too. Hopefully that gains traction and reduces everyone's power bills. :)
https://hackaday.com/2021/06/07/intels-atx12vo-standard-a-st...