The dGPU: Killing Battery Life

The 15 and 17-inch MacBook Pros have a discrete GPU that only turns on if you fire up an application that really needs it—at least that's how it is supposed to work. In practice, the discrete GPU takes over control if your application uses any one of a number of frameworks—and some of the time, the dGPU simply isn't necessary.

Case in point, launching Chrome won't trigger a dGPU switch but the moment it encounters Flash the discrete GPU will take over. The bad news is that even if you close all Chrome windows, the dGPU won't power down until you quit chrome entirely. The same is true for Photoshop. Launch the application and you're still on the iGPU. Actually open up an image and the dGPU takes over. Even if you close all open images and just leave the Photoshop application open, the dGPU won't relinquish control. FaceTime and anything using the integrated camera also require the dGPU, despite it being totally unnecessary.

If you connect any external display to the 15 or 17-inch MacBook Pro that also forces the dGPU on, at which point both the integrated panel and external display are driven by the dGPU. There is no funny frame buffer copying going on, both the integrated and discrete GPUs have their own connection to the display.

Apple also fails to provide a way of turning off the dGPU by default—the best you can do is shut off the iGPU and just use the dGPU entirely. Thankfully Cody Krieger's gfxCardStatus tool gives us exactly what OS X does not. Version 2.0.1 adds support for the 2011 MacBook Pros.

I'm going on and on about the dGPU because it's state can seriously impact battery life. The numbers below should help put that in perspective for you:

Impact of Discrete GPU on Battery Life
15-inch 2011 MacBook Pro Light Web Browsing Flash Web Browsing
Integrated GPU (Intel HD 3000) 8.85 hours 7.03 hours
Discrete GPU (AMD Radeon HD 6750M) 5.67 hours 2.97 hours

Even just browsing the web, the dGPU being on drops battery life by 35—60%. Under full CPU load I suspect the percentage difference would be smaller, but still significant. The worst part of this all is that without gfxCardStatus you can negatively impact battery life by doing something completely innocent like accidentally leaving an application open. Given how much OS X is tailored to simply closing windows when you're done with them and not quitting applications, an overly aggressive dGPU can really be an issue.

Thankfully we do have gfxCardStatus but there's honestly no reason Apple shouldn't include this functionality with OS X from the start.

The GPU Comparison Display Quality
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  • ImSpartacus - Thursday, March 10, 2011 - link

    Apple doesn't do something unless they can do it 100%.

    They won't default to SSDs until they are on the logic board like the MBA. We'll probably see the disk drive go at the same time.

    Maybe Apple will continue to use hard drives for storage? That might be the reason we are still seeing 5400rpm drives. Apple doesn't want to upgrade everyone to 7200rpm drives only to have 5400rpm drives the next year, even only for storage.

    But who knows?
    Reply
  • Tros - Thursday, March 10, 2011 - link

    I imagine they'd go for the MBA-SSD and the larger platter-based storage, and just partition. But to do that smoothly, they need a better partitioning system (to keep it user friendly); ZFS. Reply
  • Nentor - Friday, March 11, 2011 - link

    Apple doesn't do something unless they can do it grand (or make it seem grand).

    Why put in SSD standard if they are still a luxury? As long as the average pc user is not fully aware of what SSD are and what are the great benefits you can still demand premium for them as an upgrade for people that do want one.

    Just watch, when SSD are becoming the standard Apple will put put them in and market the hell out of it and make it fit the whole Apple image.
    Reply
  • dsumanik - Friday, March 11, 2011 - link

    Dude, if your hdd is integrated into your mobo... Not only do have the disadvantage of not being able to upgrade to faster/larger capacity drives...

    If the disk fails you need to replace the whole board - $$$
    If something on the board fails, you lose all your data - facepalm
    Apple dictates the price of of the hdd, even when it's a yer old - $$$

    A simple, 2 screw user replaceable hdd is the elegant solution and always will be.

    Wake up peeps...

    They aren't supporting other drives because they want to sell you outdated technology at a higher price.... End of story.
    Reply
  • JasperJanssen - Monday, March 14, 2011 - link

    Dude, do you even have a vague clue what you are talking about?

    The MBA doesn't have an SSD soldered onto the mainboard, it has it on a standardised daughter card. And by standardised I don't mean standardised by Apple, although to be fair Apple is the main supplier of machines using it at the moment. It's a card not unlike minipci(e), and entirely swappable from one machine to a replacement. Also, Apple isn't the only one supplying these drives.

    It's entirely possible that other thing&light manufacturers will start using them, as it's a very useful form factor.
    Reply
  • KoolAidMan1 - Thursday, March 10, 2011 - link

    There is no dedicated GPU in the 13" MBP because there isn't room for it. Look at other notebooks in the same size and price class such as the Lenovo x220. Same situation, integrated GPU only. An dedicated GPU means bigger motherboard, which defeats the purpose of notebooks that are so small. Reply
  • Wieland - Thursday, March 10, 2011 - link

    Sandy Bridge laptops haven't been on the market very long. It's way too early to make a conclusion about what is and isn't possible in terms of size. That said, the Sony Vaio S is basically the exact same size, lower weight, lower price, and offers almost as much battery life, and it is configurable with two different versions of AMD Radeon Graphics (6470M, 6630M). The new Vaio Z will probably be even more impressive in this regard. Reply
  • ltcommanderdata - Thursday, March 10, 2011 - link

    The 13" MacBook Pro is a constant 0.95" thickness. The Vaio S ranges from 1.08" - 1.24" thick, a 14% to 31% difference. So the 13" MacBook Pro has significantly decreased internal volume which will definitely constrain how you lay out internal components and the thermal room on the machine impacting whether it's worthwhile to put in a discrete GPU. Reply
  • claytontullos - Thursday, March 10, 2011 - link

    Have you dealt with HP's tech support? It's like pulling teeth to get anything done.

    My ram in my Dv4 was bad, it would randomly cause windows to crash both in Vista and Windows 7. My ram failed memtest86 with over 4 million errors after a few minutes of testing... however my ram would pass HP's 5 second ram test with flying colors.

    HP's support first insisted I revert my laptop back to Vista and in any event would not service my laptop because the ram passed their "test."

    I will never buy another HP product.
    Reply
  • quiksilvr - Thursday, March 10, 2011 - link

    I won't judge a race based on the actions of few. At the same time, I won't judge a company just because one of their products didn't work that well for me. That's like saying I bought a 4 pack of Duracells and one of the batteries weren't working so now I buy Energizer.

    And to be fair, it isn't like HP made the RAM. If you were getting random crashes, you obviously didn't do anything and are clearly under warranty. Simply say "I turned it on and it keeps crashing" and they'll say "Okay here send it back" and 9/10 they will pay for shipping (depending on where you got it from).

    Now I'm not an HP fanboy (far from it, I own a Lenovo), but prior to that I owned a zd8000 for about 5 years with no problems. Does that mean that HP is utterly flawless and no one makes a product like them? No. But I know quality when I see one and I stand by what I said: The Envy 14 is probably one of the best laptops you can get. Hell, it's only $999 and it blows the MBP out of the park.
    Reply

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