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Apple Mods Intel Chipset for Auto GPU Switching

When Apple announced that its new 15- and 17-inch MacBook Pros had both the Intel HD IGP as well as a discrete Nvidia GT 330M GPU and it could switch seamlessly between them automatically, we assumed that it was using the Nvidia Optimus technology – but it isn't. Instead, Apple brewed up its own software solution, which works in a slightly different fashion, Ars Technica reports.

While Nvidia Optimus uses a software-driven list of apps that would trigger a system to switch over to discrete graphics, Apple's solution detects on the OS level whenever OpenGL, Core Graphics, Quartz Composer are in use and calls in the discrete GPU to help.

Another way Apple's method differs from Nvidia's system is that Optimus runs the discrete GPU's display through the IGP's frame buffer. This requires that both the GPU and IGP to be active, as well as taking up a lot of traffic on the bus. Apple's solution deactivates the Intel HD graphics whenever the GT 330M is called upon, helping it be a little more power friendly.

Apple credits its control over software and hardware as the main reason why it is able to offer an arguably better solution to automatically switching graphics. In fact, Apple appears to have modified the baseline HM55 Express Intel chipset to accommodate for this more advanced switching technology, according to a teardown done by iFixit.

Sadly, Apple doesn't offer the user full control over which graphics part run and when. The quoted battery life is 8 hours when running the GT 330M and 9 hours when it's Intel HD IGP only. Although the user can select between auto switching and having the GT 330M run full time, the option to disable the discrete GPU for the sake of prolonging battery life (like being able to switch off Bluetooth or Wi-Fi) doesn't exist.

Marcus Yam
Marcus Yam served as Tom's Hardware News Director during 2008-2014. He entered tech media in the late 90s and fondly remembers the days when an overclocked Celeron 300A and Voodoo2 SLI comprised a gaming rig with the ultimate street cred.
  • cabose369
    Someone should sue Apple for modifying their computers and put Steve Jobs in jail! LOL!! (see below if you don't get it)

    "Modifying a console and computer is considered an illegal act under section 342.1 of the Criminal Code and is punishable by imprisonment for up to ten years," the RCMP said in the statement.
  • Zinosys
    Mmm, interesting. I wonder what Intel has to say about this...

    But this looks neat. I don't see what's wrong with that, save the fact that you can't disable the 330 for battery purposes. Maybe we'll see a driver update in the future.

    Looks interesting nonetheless.
  • cabose369
    ZinosysSaying that Steve should go to jail is pretty far out. That's a bit silly. I really doubt anything definitive is going to happen. (as we well know, Apple's legal team knows how to bend laws a bit).
    It was a joke......
  • Zinosys
    cabose369It was a joke......I take people too seriously :|
  • cabose369
    ZinosysI take people too seriously :|

    It's hard to tell over the internet.
  • mianmian
    cabose369Someone should sue Apple for modifying their computers and put Steve Jobs in jail! LOL!! (see below if you don't get it) -jail.aspxHum.... I have to say Intel does not sell COMPUTER to Apple, only chipset & CPU. So it teaches us a way to void be in jail: Do not buy a whole computer. Just buy parts and make our own computer!
  • tpi2007
    So Nvidia is in real trouble... if Microsoft decides to do the same in partnership with Intel, there goes Optimus down the drain...

    add Tegra that isn't doing too well, GTX4xx that are out of stock everywhere (newegg, etc) or not even in stock at all: for example says "The item has not yet been released" (both GTX 480 and 470):

    Whereas says they will dispatch within 1-2 months (yes, not 1 to 2 weeks, they are talking months, Semiaccurate was right all along)

    Don't believe it? Check it out: both GTX 480 and 470:

    Nvidia is in deep trouble. This is bad for the competition. Good for business though. Intel might buy it in a few months.
  • dragonsqrrl
    Not sure if I'm reading this wrong, but Optimus does seem to have one significant advantage over Apple's solution. It's capable of shutting off the discrete GPU when only the integrated GPU is needed. This means seamless and automatic powering up and down of the discrete GPU, and not just placing it into a state of hibernation.
  • dannyaa
    Marcus - really? The OS intelligently auto detects when to turn off the discrete. The only time you would want manual control is if you NEEDED the power but would rather have one extra hour of battery life (assuming you used the computer's full charge for this given task). Who in the world would want one extra hour of battery life so they could play their game at 15fps?

    This is great. They built in a better solution into the core of their OS to improve the end user experience, and made it completely transparent.
  • phatboe
    dannyaa: you are assuming that the only time one of those API's (OpenGL, Core Graphics, Quartz Composer) are called is when the user is playing a video game. Not everyone plays games, hell Macs don't even have that many games to play on it. Those API's could be called for other reasons and maybe those other functions don't require the full power of the discrete card. In that case it would be better to have the ability to disable the discrete card for power savings.