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I noticed that running with the discrete GPU uses more power and generates more heat. I just need the discrete GPU to drive an external monitor, I'm not concerned about performance.

By controling the power state I expect to control the voltage and frequency of the GPU. This could be achieved by either changing the power state of the GPU or the voltage and frequency directly.

I just want to make sure that the MBP runs as cool as possible.

xpereta
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I use gfxCardStatus to see and control if my discrete GPU is in use. Is that what you want?

To see how much power is consumed you can use iStat Menu for example...

TooAToB
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    I already use gfxCardStatus, but when using an external monitor only the discrete GPU can be used. And I use iStat Menu to check the power consumption. I'm more interested in seeing the actual state that the GPU is on, and changing it to use as low power as possible at all times. – xpereta Nov 15 '13 at 10:30
  • What do you mean by state exactly?

    I don't think it's possible to control the GPU any further, it does what has to do, I guess... Saving energy by switching GPUs when possible is controlled by the system.

    For external monitors it needs to use the discrete GPU as you say, I'm not sure about that, because also 2011 MBP without discrete GPUs are able to connect multiple monitors. On the newer Models also the onboard Graphics may be used per default to handle external monitors. Have you tried to stop using the discrete graphics with gfxCardStatus while connected to your external monitor?

     – TooAToB Nov 15 '13 at 10:40
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    I mean that the GPU may have different states that control the voltage and the frequency that it runs at. Depending on the software running the GPU uses more voltage and runs at a higher frequency. I know I can change the voltage and frequency on this 2011 MBP on Windows, but I don't know a way to do this on OSX. I have updated the question. – xpereta Nov 15 '13 at 10:43
  • I have verified that the external monitor is not usable when the internal GPU is in use. – xpereta Nov 15 '13 at 10:47
  • I accidentally hit enter to early above... made an edit.

    I don't think there's an easy – if any – way to do this under Mac OS X, but I also don't think it's necessary or useful. Normally Apple puts a lot of effort in such things, so the user doesn't need to care about it. Plus, if it's even possible, I wouldn't recommend, as it could cause serious instabilities for your system.

    Why exactly do you want to control it manually? Does your MacBook consume more power than it should?

     – TooAToB Nov 15 '13 at 10:51
  • Ok thats kind of weird, I just tested it with my 2012 MBP (Intel HD 4000) myself: Even if I do a full 1080p Airplay Screen Sync to Apple TV it uses the internal Graphics... – TooAToB Nov 15 '13 at 10:53
  • I intend to make it run as cool as possible. I don't want to have the fans running constantly (I know I can control the speed of the fans, and I'm using a support to increase the airflow) – xpereta Nov 15 '13 at 10:57
  • If you're MacBook turns it's fans higher than idle when an external monitor is connected that looks more like an airflow problem. My GPU hasn't ever caused the fans to speed up (never was warmer than 75 degrees Celsius, as far as I remember). When the fans speed up, its mostly caused by massive CPU load.

    If you dare to open up the Macbook and look inside if there's to much dust stuck somewhere in the heat pipes or fans, try that. I recently had a Late 2011 MBP of a friend to set up a fusion drive and in 2 years of use it has caught a lot in its cooling system...

     – TooAToB Nov 15 '13 at 11:05
  • Update: My MBP has fallen victim to the well known defect in the GPU in the 2011 models. It's not clear if it is a defect in the GPU itself or the result of a badly designed cooling system. – xpereta Jan 28 '15 at 11:18