Limiting the MAX fan speed on the MBA via smcFanControl

Discussion in 'MacBook Air' started by Scott6666, Apr 9, 2008.

  1. macrumors 65816


    Feb 2, 2008
    I saw an interesting post today by pgharavi who says he is using SMCFanControl to set the max speed of his fan to 4000RPM:

    Not to question his knowledge but have others tried this and does it really work?

    I might not go so far as to set the fan to 4000 (but I might). Given all the thoughts on Coolbook, what do you all know/think about this? Safe and effective relief from fan headaches?
  2. macrumors regular

    Nov 25, 2004

    I thought about making a thread but I've been too busy. I would suggest changing the topic title to something akin "Limiting the MAX fan speed on the MBA" to get more attention to the specific issue.

    Anyway, the app, by itself, will NOT keep your MBA quiet. The GUI purposely doesn't allow you to do this (see the FAQ).

    Like I said in the previous topic, you can also increase the max fan speed using terminal.

    Thanks for making the topic.
  3. macrumors newbie

    Mar 30, 2008
    Cool. I might try this tonight.
  4. macrumors regular

    Oct 22, 2005
    how do we write a script that runs this command during startup and after waking up from sleep?
  5. macrumors regular

    Nov 21, 2006

    I thought this was a hack for SMCFanControl, meaning that whenever it runs (as on startup) this fan-limiting script will be active? I haven´t tried it yet, so sorry if this is an embarrassing assumption :)
  6. macrumors regular

    Nov 25, 2004
    I actually don't have the app running at all. It's not necessary for the terminal command.
  7. macrumors regular

    Nov 21, 2006

    That means that you will have to reapply the script in terminal after reboot and wake froom sleep?
  8. macrumors regular

    Nov 25, 2004
    I made a script and instructed the MBA to run it after boot. I wanted to upload it here but the forum won't let me. It's a simple automator script that auto runs at boot and then closes itself.

    If I watch a movie, I just open terminal and enter in the full speed command.
  9. macrumors regular

    Oct 22, 2005
    do you mind giving us the script for us?

    i'm new to mac and have no idea how to run the script automatically..

    it isn't like windows where you can just put .bat file under "startup" folder..
  10. macrumors regular

    Nov 25, 2004
    I didn't know either until like 2 days ago ;)

    Just go to Automator, choose custom, and then find terminal or whatever. Then paste in the command from the OP (for 4000 RPM). Then save it as an app, and then put it anywhere you want (I leave mine in Docs).

    The final step is to go to your system pref., and then Accounts, Login Items, and then add your little app you just made.
  11. macrumors member

    Oct 25, 2007
    hey where in the automator list can you find Terminal... I can't find it anywhere...

  12. macrumors regular

    Nov 25, 2004
    Custom > Utilities > Run Shell Script

    That's where you paste the command. Delete the 'cat' text in there first.

  13. macrumors member

    Oct 25, 2007
    Works like a charm!! thanks!!!
  14. macrumors newbie

    Dec 14, 2007

    Thanks on the tip regarding the fan control as well as the automator tip.
    After purchasing coolbook, this is exactly what i need.

    Instead of putting the automator app at login, i created an automator app that drops the fan to 4000rpm, waits for 10 seconds and returns the setting to default 6200rpm. Im still afraid to set it at 4000rpm all the time. I just need this to tell the macbook air to shut up for awhile. Once it hits 4000 rpm, it usually doesnt go back up and just hovers around 4500rpm.. which is good enough for me.
  15. macrumors member

    Oct 25, 2007

    What a chicken!!!!!

    nah , just kidding.... whatever makes you feel comfortable! but don't you notice that when at 6200rpm the CPU is running in the low to mid 60 degrees?? I don't understand this.
  16. macrumors member

    Nov 11, 2007
    Don't you guys think that limiting the fan speed is just plain asking for trouble?

    The fan is running at that speed to cool the machine off. Sacrificing cooling just to quiet the machine down might toast it.
  17. macrumors regular

    Nov 25, 2004
    No, it's fine. Like I said, if you are doing wireless productivity, the gain is usually only 1-3 C. Nothing.

    Even watching videos the gain is 5 C max. But for that, I would, and do, put the fan back up to 6200.
  18. macrumors member

    Dec 12, 2007
    Hi, I would like to know if I can set the fan up so that they won't rotate over 2500 rpm and not just 4000 rpm. Is it possible ? It seems the command line for 4000 rpm is "3e80". Should I write "2e50" ?

    I ask this question because I am very sensitive to noise and really bothered, even at 4000 rpm. And since I have changed the thermal paste and use coolbook I intend to limit the maximum temp at 80 degrees (even if it means that the processor would have to slow down, because the stuff I do on my MBA is not processor intensive).

    Thank you for your answer !
  19. macrumors regular

    Mar 27, 2008
    So after you reapply thermal paste and use coolbook, the fan speed still high? mind to share the temp and fan speed after you did both? I'm also bothered by fan noise, but if using coolbook and reapply thermal paste (as in your case) still won't make the Air quiet, i may as well give up and live with it. Thanks!
  20. macrumors member

    Dec 12, 2007
    Actually it depends on your usage. You might feel fine if running CPU-only intensive tasks since the fan only turns on when the CPU go over 70 degrees or the heatsink 55 degrees (at least on mine).

    Though, if you plan running graphic average intensive tasks (such as a MP4 file), then the fans will turn on quickier because you will be using the integrated chip for Core Image, thus resulting in a superior increase of the heatsink (and not CPU) temp.

    This is why I am now able to encode a DVD with Handbrake with very little fan noise but unable to watch the resulting MP4 file without the fans rotating over 4500 rpm !

    EDIT : In addition to my previous question, do I have to install SMC fan control even if running the app itself is not necessary ?
  21. macrumors regular

    Nov 25, 2004
    I think so. Notice the command references the application. As per your earlier Q, I don't know. there is command (I think it' -h) that will tell you the command for all
  22. macrumors regular

    Mar 27, 2008
    Did you try limiting the fan speed to 2500 Maya? What's the max temp you've seen after limiting the fan to such low speed?
  23. macrumors regular

    Nov 25, 2004
    I would imagine that it would be damn high.
  24. macrumors member

    Dec 12, 2007
    Well, I have not been able to determine the hexa code for 2500 so I am currently at 4000 rpm, encoding a DVD with Handbrake. The CPU temp is 76 degrees and the Heatsink 63 degrees. I use CoolBook to throttle down the CPU to keep the temp under 75 degrees, so now my CPU is at 800 mhz, which is fine for me : why would I need handbrake to be faster if I encode during the night ? Moreover, with the fan set at 4000 rpm I can sleep while encoding :).
  25. macrumors regular

    Nov 25, 2004
    You could email the app creator.

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