Mac keeps its power promise, PC challenge issued:

I have a duty to report that this figure is inaccurate. Results of the measurements I took on a 20-inch iMac were better than Apple’s specs.

At typical interactive use–both hands in constant motion, flipping among 6 or so open apps–iMac draws 80-85 watts. With both of Core Duo’s cores cranked to 100 percent utilization, I got a steady 95 watts. Lightly or heavily loaded, you can use iMac as a reading light and still save on your electric bill.

Let’s jot 95 watts in the margin. My wife’s standalone 19-inch LCD measures in at 32 watts, including the green power LED. To approximate the power the 20-inch iMac’s would consume if it were a generic headless PC, take iMac’s loaded 95 watt draw and subtract 32 watts for the display. That leaves you with…

…a 63 watt personal computer. That’s with two 2 GHz cores kicking at 100 percent, 802.11g and Bluetooth active, 1 GB of RAM and 128 MB of GDDR3 graphics RAM all churning away.

Well, my imac is using less than my lights I have on now. And I don’t use the wireless settings… Love to see the energybill this year Those PC people that buy 300/500 Watt power supplies for a headless PC…