On 3/3/2017 11:31 AM, Jeff Liebermann wrote:
On Fri, 03 Mar 2017 01:46:08 -0500, Bob Engelhardt wrote:

Unless my Kill-a-watt is wonky.

That's a possibility. I have several kill-a-watt meters. ...

I checked my Kill-a-watt against my Fluke "True RMS" clamp-on. They
read the same current, so that gives me a lot more confidence in the
Kill-a-watt.

Now, for the "I'm feeling really stupid" part: in the maze of cables
under my desk, I had put the Kill-a-watt on the wrong one! I was
measuring the power on everything: PC, printer, modem, etc.

When I used the right cable & measured just the PC, the power was
155W+-. Versus the 200W previously. So my PSU efficiency is 33%+-
(54/155). Better than the previous/wrong 25%, but not dramatically so.

Thanks to all the commenters.

Bob