Mac and PC Power Consumption

I’m thinking of buying a new computer for home and thought I’d actually check power consumption (for a change) after noticing that (1) my work PC never goes to sleep despite my settings (I think it’s because it has a web server running on it as a “service”), and (2) a rather nice Gateway (Acer) tower I was looking at had a 750W power supply… I mean, 750W is enough to run a fan heater on low, or the same heat output as ten people.

Here’s what I’ve learned so that you don’t have to bother.

Computer Idle (Watts) Max (Watts)
Mac Pro (original) 4×2.66 (1) 171 250
Mac Pro (2008) 8×2.8 (1) 155 318
Mac Pro (2009) 8×2.3 (1) 146 309
Mac Mini (2009) 2×2.0, 9400M (1) 13 110
Mac Mini (Late 2006) 2×1.83, GMA950 (1) 23 110
24″ Intel iMac (2, 3) 80-100 135 (or 240?!)
PC Intel Core 2 Duo E6400, 8600 GTS (4) 87 163.5
PC AMD Athlon 64 X2 5000, 8600 GTS (4) 102 210
MacBook 2.4, 9400M (5, 7) 9W (8) 90W
MacBook Pro, 9400M+9600M (6, 7) 10W (8) 100W
Here's a graph in case you find digesting tables of numbers as unpleasant as I do.
Here's a graph in case you find digesting tables of numbers as unpleasant as I do.


My Kill-a-watt showed up (I got mine from So far my very rough results are that my Macbook Pro (late 2007) uses about 30-35W on “idle” (but with the screen full brightness) and the most I’ve gotten it up to is 68W, but I suspect it could get to around 90W if I could max out the GPU and the CPUs simultaneously.

It will be interesting to measure the power usage of some flat screens to see how well a Mac Mini compares to the iMac (and, at the same time, how well the iMac compares to modular options).

Incidentally, the Macbook Pro’s power brick consumes 1W when it’s not attached to the notebook, and around 24W when it’s charging the notebook but the notebook is asleep. The figures above were for a notebook whose battery needed recharging — it’s probable that power usage goes down if the battery is fully charged.

Notes and Sources

  1. Apple Computer’s tech support pages
  2. From this thread; varying peak power consumption figures probably reflect different GPUs/tasks and bad methodology
  3. Power consumption includes built-in 24″ monitor (varying idle power figures based on brightness)
  4. The Truth About PC Power Consumption on Tom’s Hardware
  5. MacBooks have a 45 Watt-hour battery and have a quoted maximum battery life of 5h when using wireless, so we can safely assume idle power consumption will be around 9W.
  6. MacBook Pros have a 50 Watt-hour battery and a quoted maximum battery life of 5h, so 10W.
  7. Guesstimate based on assumption that peak power consumption will be about 10x idle — which seems like it’s roughly right based on the Mac Mini’s peak power consumption.
  8. Edit: rereading this post I realize there’s a major boneheaded mistake in it. Since notebooks never draw power directly they will always draw (significantly) more power at the wall than they actually consume, and batteries of course take more power to charge than they later provide. I’ll update my figures and graph when my “Kill-a-watt” arrives.


I just changed the energy saver settings on the Mac Pro I’m using. Good grief!

The average cost of residential power in the US is 11.03 cents per kWh (Department of Energy statistics), so that means a Mac Pro on idle costs about $0.39 cents per day, or $141.07 per year, versus $0.04 and $12.56 for a Mac Mini (and probably a similar value for an iMac which puts its display to sleep). And note that the “typical” PC consumes over half the power of a Mac Pro while offering dramatically lower peak performance (as the Tom’s Hardware article might put it — if you were working on a video project that required 8h of manual work and then a bunch of rendering, the 8h would be slightly reduced on the Mac Pro vs. the PC (which would be running close to idle) and then the Mac Pro would finish rendering in one-quarter the time and go to sleep.

Oh, and by the way, if you buy a cheap PC and keep it for two years leaving it switched on most of the time, you’ll have paid an extra $200 for electricity compared to a Mac Mini. As I said at the outset, my work development PC is running a web server as a “service” and thus will never go to sleep.

If you want to save power (and money), get a Mac Mini or a notebook (assuming Windows notebooks are similarly frugal) — unless you need serious horsepower, in which case Mac Pros start to look good (as long as you put them to sleep when you’re not using them). If you bought a Mac Pro because you think Apple is “green”, but you only use it for fairly minor stuff and you don’t put it to sleep when you’re not using it (heck, even if you do) then you’ve made a grave error — your Mac Pro is using as much power on idle as a typical PC under heavy load. Mac Pros are great in terms of computational power per watt, but only if you’re actually using them.

Three New Things, And One More (Of Course)

Just some quick reactions to the Macworld Expo announcements.

iTunes. Well, Apple didn’t announce a new Mac Mini with a 9400M GPU, and it didn’t announce a new bigger or cheaper or somehow more compelling AppleTV. And it didn’t announce any new iPods or iPhones. But the iTunes announcement is probably going to turn out to be more significant than anything else — see the second item:

  • New pricing model. $0.69, $0.99, or $1.29 per song. This is not “pay more for 256 kbps”, but allowing Music labels to charge more for new shiny stuff and less for back catalogue.
  • Everything is going to be DRM free. (8M songs now; 10M soon.) In other words, the recording industry idiots have finally gotten a clue.
  • iPhone can now download music over cellular networks (not just Wi-Fi).

It doesn’t say whether our existing purchases will be stripped of their DRM though. I hope that devil is in the details.

The 17″ Macbook Pro looks great. I won’t buy one. When I get a notebook I’ve learned that its single most compelling feature is being small. (As small as possible without becoming dysfunctional.) There’s a perfect MacBook for me already, and it’s the new MacBook Air (which Apple quietly upgraded to the nVidia 9400M sometime in the last couple of months). Oh, and the new 17″ MacBook Pro has a non-removable battery which, apparently, gives you 8h (if you don’t use the faster GPU), and has a 5y lifespan — 1000 charge cycles — but, as already mentioned, isn’t removable.

iWork ’09 looks very compelling. The key missing features appear to have all been added (except for automatic indexing in Pages and perhaps pivot options in Numbers). It would be nice if Apple released a Tables database component but I guess that would make Filemaker’s Bento look silly. Wait, it already looks silly.

I wonder why Apple didn’t try to integrate Google documents into iWork rather than or instead of doing Do they really expect to become a major profit center? If not, why not simply leverage something very good that does much the same thing that happens to be something Google is doing as a loss leader. could be great, but how much better than Google docs will it have to be to make up for not being free?

iLife ’09 looks equally compelling. I’m one of the people who happens to like iMovie ’08 (I think we’re the silent majority). If you want to create an actual movie, iMovie ’08 is hopeless (mainly owing to poor audio functionality), but then so is iMovie ’06 (for much the same reasons). For cutting together a bunch of footage into something halfway decent in nothing flat, iMovie ’09 looks like it will let us have our cake and eat it. If the face recognition stuff in iPhoto ’09 is halfway decent it will be a huge, huge feature. Music lessons in GarageBand seem like a killer feature, but it really depends on how well it’s done.

MacBook “Helium”

Two rumors: Apple building a carbon fiber MacBook Air, and Apple building (or needing to build) a NetBook (i.e. an ultralight and ultracheap MacBook that is net-centric). Well, Apple isn’t going to sell a $400 notebook any time soon, but it might sell a $600-800 notebook similar to, but smaller than, the Air, and to keep costs down it might use plastics — I mean Carbon Fiber — and such a notebook would be smaller and lighter than the MacBook Air, so it might be called the “MacBook Helium”.

I’ll laugh out loud if I’m right. I was right about Apple releasing its NeXT-based OS as OS X way back when — I predicted they’d release a stopgap OS 9 which would make them a ton of money and keep people satisfied while they polished Rhapsody which they could then call OS X. Of course, I also wanted them to call the Mac “se/30” the Mac “sex” for similar reasons.

If Apple does release a $400 micro-notebook, I hope it’s basically a super iPhone and not a crippled Mac (or that it dissolves the distinction between the two).

Last minute Macworld speculation

Something in the air?

Something no-one seems to have considered is the possibility that Apple will announce full support for Adobe’s AIR on the iPhone (and possibly Mac OS X in general). This would make the Flash/ActionScript ecology an intrinsic part of Mac OS X, further cement Apple’s disdain for Java, and (partially) solve the iPhone SDK issue. It would also dovetail nicely with Cringely’s idea that Apple plans to buy Adobe.

Note: AIR is, in essence, Webkit + Flash.

What’s wrong with this possibility? Well, Flash is still a terrible processor hog, and it will suck the iPhone’s battery dry … unless it gets a bunch of tweaking. Another option would be to support a battery-friendly subset of ActionScript 3 (if there is such a thing) and go to an event model which doesn’t redraw the entire screen at (typically) 30 frames per second.

MacBook Air?

There are a lot of people suggesting that (a) the announcements this year will be relatively ho-hum (who can compete with the iPhone, after all?) and that (b) Apple will release an ultraportable.

It seems to me that if Apple releases an ultraportable with the obvious feature set (given its recent releases) it will be bigger than the iPhone (although people won’t immediately realize it). Imagine the following:

8-10″ ultrathin laptop running a modest but still decent cpu. Maybe multitouch, maybe funky dual screen with one touchscreen/keyboard. Whatever. (Frankly, most folks would prefer a fullish sized hard keyboard to some kind of funky DS-style exercise.) Given bluetooth support, the keyboard could be a cable-less clipon, and the unit could have a “giant iPhone” form factor.

3G cellular network support, compatible with Sprint, Verizon, AT&T.

Bluetooth, 802.11B/G/N.

32 GB of flash memory, 1GB of RAM (upgradeable to 3GB).

Battery Life: 4+h “active”, 24+h “standby”

Prices (Good, Better, Best): $1499, $1799, $2099.

OK, it’s not an iPhone. On the plus side it’s a Mac OS X notebook, it can run standard OS X software (including Skype and Vonage) and can be used as a cellphone when closed. Oh and it does video conferencing.

Maybe for bonus points it has Newton-like functionality (e.g. you can draw or take notes on it with a stylus).

iWork, iLife, etc.

There’s an assumption running that because there are already iWork and iLife “08s” out there’s nothing much to expect on the software front. We know that Apple plans an announcement at a Final Cut Pro user group meeting during the expo (possibly the successor to Shake, possibly something else like … Apple has bought a high end 3d company — Newtek or Softimage, say — and is making all their stuff Maclike).

It’s always possible that iLife/iWork will get serious revisions which don’t require existing owners to buy an update.

Quad Core iMacs

Given that Dell is currently selling quad core XPS desktops for $799, it would seem to be a no-brainer that Apple will put quad cores into at least the upper end iMacs, possibly the whole line, and possibly into a Mac mini variant.

This will, unfortunately, close the gap between the iMac and Mac Pro product lines, which makes the introduction of a headless iMac with upgradeable video even less likely.