Thermals and Power Consumption

The new MacBook Pros have the potential to draw more power than the previous generation. Despite being built on a 32nm process, the new 15 has twice the cores of last year's model—there's no question that it can draw more power under a full load.

I measured maximum power consumption at the wall using the same power brick and a fully charged battery. I chose two high-load scenarios: Cinebench 11.5 and Half Life 2. The former will fully load all CPU cores while the latter ramps up CPU and GPU usage.

Maximum Power Draw—Cinebench R11.5

Under Cinebench the new quad-core 15-inch MacBook Pro draws 70% more power at the wall than last year's dual-core model. This shouldn't be surprising as Cinebench scales nearly perfectly with core count—twice the cores should result in nearly twice the power draw. The scaling isn't perfect since we are dealing with different architectures and a number of factors such as display remain static. The new 13-inch MacBook Pro isn't as worrisome, it has 88% of the power usage of the high end 2010 15-inch MBP and 81% of the battery capacity.

Maximum Power Draw—Half Life 2: Episode 2

The Half Life 2 comparison is not quite as bad, although the new 15-inch MBP still uses 45% more power under full load compared to the previous generation. These numbers tell you one thing: although the new MBP is significantly faster than its predecessor, it can also draw significantly more power. Running the same workload the new MBP shouldn't have any problems lasting as long as the old MBP on battery, but running a more aggressive workload will result in shorter battery life as a result of the higher max power consumption. In other words if you use the higher performance to do more, you can expect your battery to last proportionally less than the 2010 MBP.


The 15-inch MBP uses an 85W power adapter (left) and the 13-inch MBP uses a 60W adapter (right)

Drawing more power also has another unfortunate side effect: the bottom of the chassis gets even hotter than before. I took some crude temperature measurements when I did the 2010 MacBook Pro reviews last year. I pointed an IR thermometer at the center of the bottom of the notebook, right where you'd have your lap, and measured surface temperature in a couple of scenarios.

Surface Temperature—Web Browsing

While browsing the web with tons of windows/tabs open I noticed a small but tangible increase in surface temperature of the 2011 15-inch MBP compared to the 2010 model. Even the new 13 is warmer than last year's 15. Under light workloads none of these temperatures are high enough to really be a problem.

Surface Temperature—Half Life 2: Episode 2

Load up the system however and you start getting into the uncomfortable zone. The new 15 breaks 38C, while the new 13 is actually only marginally warmer than the old 13 thanks to the use of Intel's HD Graphics 3000.

Max Temperature—Half Life 2 Episode 2

The biggest difference I noticed was the max temperature near the exhaust fan(s) on the notebooks. The new 15 is a whole 13C warmer than last year's model.

There's no way to get around it—if you're going to be using these systems to anywhere near their potential, they are going to get significantly warmer than last year's. Also, as a result, the new systems are noisier. Fans are more likely to spin up and given how small they are, they are quite audible. If this is a deal breaker for you, the best advice I can give you is to wait for Ivy Bridge.

Ivy Bridge will bring mild updates to the Sandy Bridge architecture, an increase in performance but more importantly it'll bring Intel's 22nm process. At 22nm I'd expect somewhat lower power usage than what we're seeing here today. Ivy Bridge is expected to ship in the first half of 2012, with updated MacBook Pros arriving ~2 months post introduction.

FaceTime HD Cameras Battery Life
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  • tipoo - Thursday, March 10, 2011 - link

    Its a shame that their base 15 inch, a 2000 dollar laptop, has a 256MB card by default. Even for non-gamers, that's starting to become a bottleneck. Especailly as this "pro" machine will make it into the hands of creative professionals, doing video work, rendering, mudbox, etc.

    Interesting about the performance differences in the HD3000 and 320M under Windows vs OSX.
    Reply
  • tipoo - Thursday, March 10, 2011 - link

    p.s whats an SNB GPU? Is that a typo? SB, perhaps? Reply
  • Brian Klug - Thursday, March 10, 2011 - link

    When we say that, we're just referring to the Sandy Bridge (SNB) GPU. Essentially it's shorthand for the Intel HD Graphics 3000.

    -Brian
    Reply
  • IntelUser2000 - Thursday, March 10, 2011 - link

    The official short form for Sandy Bridge is SNB, not SB. SB is South Bridge. Reply
  • dcollins - Thursday, March 10, 2011 - link

    For some reason Sandy Bridge is alway abbreviated as SNB. It took me a while to figure out. Reply
  • KoolAidMan1 - Thursday, March 10, 2011 - link

    The baseline 15" MBP is $1800, not $2000.

    In any case, it is an unusual update. Usually the performance delta between MBPs hasn't been so extreme. The last generation had a common GPU between all 15" models, the main difference being video RAM. Now they have completely different GPUs, one being REALLY fast and the other not much better than the one that was in the models from last year.
    Reply
  • saleem.kh - Sunday, March 13, 2011 - link

    Dear, please consider approximately 9.5% US Sales Tax on $1,799. Then total price reaches to $2,000 approx Reply
  • PeteH - Monday, March 14, 2011 - link

    There is no such thing as US Sales Tax, only state and local sales taxes. State rates range from a low of 0% to a high of 8.25% (I don't happen to know the range of local sales taxes). Adding 9.5% to the price of a computer seems completely arbitrary. Reply
  • turtle44 - Thursday, June 02, 2011 - link

    sales tax in NY,NY is 11% don't say what you don't know. Reply
  • sfdiesel - Monday, July 25, 2011 - link

    Sales tax in Portland, OR is 0%. So, adding 9.5% to the price of a computer does seem completely arbitrary.

    Do say what you don't know.
    Reply

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