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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  • iwod - Friday, March 11, 2011 - link

    iPad is only just starting to sell and iPhone still has lots of space to grow. The trend is Apple are making more units and more money from ARM specific products.

    Nvidia has just recently stated that Project Denver will be ARM 64 bit. And aiming at HPC and Desktop. Full Compatible with current ARM instruction set.

    Currently Apple must have a ARM version of Lion testing, and few years down the road, they could switch their Mac over to ARM 64 bit. Using a single Instructions Set for their whole product line.

    For some reason i have been thinking that Apple and Intel aren't doing too well together like anand has felt. I dont think Thunderbolt is any indication of their current relationship. it is merely they have been working on it for such a long time, no one wants to lose our at the end.

    Of coz it could have been the other way round x86 moving into iPhone, although that depends how much intel is willing to bend towards apple.
  • jbh129 - Friday, March 11, 2011 - link

    Anand,

    Can you guys run your high-end 15 through the Windoze tests that were used on the 13?

    Thanks
  • tajmahal42 - Friday, March 11, 2011 - link

    Hello guys!

    First, I have to say this review is really awesome, as usual! Just what I was hoping for. The thoroughness and practical sense of your reviews continues to amaze me every single time.

    For the 13" MBP, you mention "bouts of instability". Can you elaborate on that? Stuttering? Crashes? In what way do you notice that instability? I'm a little concerned now.
  • tno - Friday, March 11, 2011 - link

    +1
  • alent1234 - Friday, March 11, 2011 - link

    my wife has been bugging me about our wifi since we moved and get a poor signal in a lot of the new apartment. told her i can get a new router with 3 antennas but we will also need a new laptop as well with the antennas to take advantage of it.

    which brings me to my question. i know the 15" model has the 3 antennas. does the 13" do MIMO as well?
  • tipoo - Friday, March 11, 2011 - link

    They all use the new card.

    By the way, have you tried switching wifi channels, or installing DD-WRT and boosting signal? Even so, you don't need a new laptop after getting a new router if signal strength was the only problem.
  • alent1234 - Friday, March 11, 2011 - link

    i'll try that, thx

    a lot of wifi around me these days. we only have work laptops now so that would be our only personal computer if we bought one. i was looking for the cheap SB models when they come out
  • name99 - Friday, March 11, 2011 - link

    "told her i can get a new router with 3 antennas but we will also need a new laptop as well with the antennas to take advantage of it."

    This is not completely true. A base station with multiple antennas CAN do the equivalent of phase-array beam steering to direct most of the output power towards the target laptop. The laptop will thus see a stronger signal, and one of the better modulation schemes (eg 64-QAM 5/6) can be used rather than one of the weaker schemes. Thus your laptop, even if it has only one (or two) antennas can still see better performance.

    Note, this is a theoretical possibility. I do not know the current state of the art in how well base stations utilize the various forms of transmit diversity that are available. And no review ever seems to talk about this stuff, either by testing how well the kit works with a single antenna device, or by talking to the manufacturer about what's in their product.
  • Brian Klug - Friday, March 11, 2011 - link

    The 13" does have 3x3 MIMO as well, the exact same broadcom solution as the 15" I tested extensively.

    -Brian
  • 7Enigma - Friday, March 11, 2011 - link

    Anand and crew,

    I am very disappointed with the battery life numbers in this review. This is the first review of a laptop where it appears you have used a 3rd party app (Cody Krieger's gfxCardStatus tool) to significantly inflate the numbers of the new 2011 systems. 35-60% by your own numbers back on the discrete GPU battery life page, which you then fail to report in the battery life tables later on!

    When you are tasked to review a system (especially an Apple product I might add) it should be reviewed as is, with no tweaking or 3rd party add-ons to boost performance/benchmarks. When have you EVER installed an add-on for a Windows-based laptop to improve performance/life? I can't think of one.

    At best this was a simple oversight where you have benchmark numbers WITHOUT the gfxcardstatus, at worst this was a cover-up job which I have always argued in the forums against and on your site's behalf.

    Please update the tables to show what a stock newly-purchased laptop at the Mac Store would deliver.

    I am very disappointed in this coverage.

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