Similar to the other thread about electricity thirsty Macs, this one is about the camels of the Mac world.

Which Mac do you use that has the lowest power requirements?

I'm largely expecting these responses to be PowerBooks, but I'm very interested nevertheless.

I'm sure not everyone has the equipment to measure the power usage of their Macs (I sure don't), but you can make a quick guess at it. Your Mac will never exceed your PSU's rating (you'd blow a fuse otherwise). Given that my PowerBooks G3 (Wallstreet and Pismo both) have a 45 W power adapter, I can be relatively assured I never exceed 45 W on the PowerBook. At that, the 45 W must only be met when the battery is being charged, I'm spinning the HD, I've maxed out the RAM, I'm reading a CD or DVD, and I've got the display at full brightness. Of course, that is rarely the case, so even 45 W is probably an unlikely scenario.

So there's my answer. My least power hungry Mac is likely my Pismo or Wallstreet (or 5300 or 1400 or 3400, but you get the idea).

What about you? For your reference, the iMac G5 can only put out up to 180 W.

Peace,
Drew
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Power to the PowerPC!

I tried to find how much my Acer laptop takes, just as a comparison as I'm sure it uses a lot of power for a laptop, but its adapter only says "Output: 19 V [some squiggles] 9.5 A", so I don't know what the wattage of it is. As for my least power hungry Mac, that must be my Duo 230 - not only because I don't have an adapter for it at the moment, but because it's just so small and doesn't have a lot of the things that most laptops have.
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Main system: custom C2D 2.66GHz tower/4GB RAM/2600XT 512 MB/500GB HD/XP Pro x86+Vista Business x64
Main Mac: Beige G3 minitower (Sonnet G4 500MHz/640 MB DVD/USB/Radeon 32 MB/OS 9.2.2+10.4.11)

My least power-hungry Mac would be my trusty Quadra 650. Of course, I could say the PowerBook Duo 230 that I have would trump it, especially since it's not running so it's not really consuming any power, but I would rather focus on working Macs.

In this vein, you may enjoy this page: http://www.ppcmla.com/press/

Feel free to comment...

Peace,
Drew
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Power to the PowerPC!

I'd have ot say my least power hundry Mac would be the Pismo, or if I ever get it working, either the Mac Portable or the Mac Plus.

I should look at the ratings of the Mac LC PSU, surely they are pretty miniscule, compared to, for example, my iMac. (though its CRT may offset that small power consumption of the LC.)
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[Insert Cool Signature here!]

According to apple-history.com the two LC475s I use as servers are 30 watts apiece, which is pretty darned efficient... the LC575 in the "office" is 40 watts, including the built-in display.
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[LD8] Luddite's Cave BBS : telnet LD8.org

I can measure the true RMS, but not the effective phase of the 120 volt AC line current with my Fluke 8060A DVM.

For calibration and comparison, a compact fluorescent rated 120V 14W .200A was measured after it had completely warmed up and it draws 200 mA, amazingly. The power can be considerably less than the product of volts times amps might indicate, 120x.2=24W maximum which would occur only if all the current was in phase with the voltage sine wave. Line voltage times RMS current is an upper limit on power drawn by the combination of power adapter and powerbook.

Incidentally this particular CFL is supposed to produce the equivalent light of a conventional 60W bulb, which I also measured and which draws 492mA (volts times amps 120x.492=59 and this is likely also the approximate watts, since the filament is almost but not exactly resistive, because it is heating and cooling each cycle).

True RMS 120V AC line current consumed by my PB1400 with M4896 adaptor, Proxim WiFi PC card and Sonnet G3/333 Mhz, 64MB mem, empty internal floppy drive: charging: 500mA, accessing Internet: 225mA, idle, fully charged battery, WiFi card inserted: 180mA

We can deduce the following upper limits on my Powerbook plus 45 watt M4896 adaptor total power watts: charging: 60W, accessing: 27W, idle: 22W.

Note that the charging measured above was not necessarily at the highest possible rate since the battery was nearly charged and I do not know the rate of charge for a really discharged battery, and it's too late tonight for me to go get one to try.

So: usable Internet performance at 27W or less.
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SE30, PB1400, PMG3DT, PMG4

My iBook uses the least power.

If you're comparing a desktop system and a laptop, don't forget to include the monitor

The iBook that I'm posting from is pretty efficient. As for second place, that would either be my LC or Classic II, although I'm pretty sure my C2 uses less than my LC.

Power hungry is a subjective thing that can't be measured purely by watts of power consumed. A powerful machine that consumes more energy might take less time to perform a task than one that is slower so if you turn it on, perform the task, then turn it off as soon as it is finished the more powerful machine may actually consume less energy because it is not left on as long.

Not only that, but the rating on the power supply is the maximum, not the average. Just because my MacBook Pro brick says 85W doesn't mean it's constantly drawing 85 Watts! (In fact, plugging it in to my handy Kill-A-Watt, my MBP is drawing only 37 Watts right now.)

As it's the only Mac in the house on right now, it would win.

But the likely winner in my whole collection would be the PowerBook 100, which draws only 10 Watts when running using the hard drive, and a night-light-jealosy-inducing 5 Watts when running off RAM disk.

And to go with Quadraman's line of thought, yes. You must take work done per watt in to account as well.

For example, my MacBook Pro may draw close to 80 Watts under full load, while my dual-socket workstation draws closer to 400 Watts.

But my dual-socket workstation can get video encoding done quickly enough that total Watt-Hours expended encoding video is lower for the workstation than for the notebook.

Work-per-watt is a meaningless measurement to most people. Most people don't turn off their computer when they are done - they just leave it running and walk away. If your energy saver settings are good, they'll suspend or sleep the computer after a while, but some apps (like iPhoto on my iMac for some reason) induce insomnia.

If you read the original post, you'll see that I admit my math is coarse and worst-case only, and that actual, real-world measurements would most likely be lower than the rough maximum I calculated based on PSU specs.

I recently put my Pismo and my Wallstreet on a Kill-A-Watt and saw that with reasonable processor loads, they both sip about 18W. I got to 45W by charging the battery with a screen on full brightness. So by the work-per-watt measurement, the Pismo would win. But by instantaneous (not Watt-hours, but Watts) measurement, it's a draw.

Peace,
Drew
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Power to the PowerPC!

I would have to say it would be any one of my laptops (pismo, 1400c, duo 230, etc). They all use a 45W adapter.