uMBP internal temp difference (lid open vs lid closed)

Discussion in 'MacBook Pro' started by sn0warmy, Sep 4, 2009.

  1. sn0warmy macrumors 6502a


    Mar 26, 2009
    Denver, CO
    I was considering picking up this stand for my uMBP:

    One thing that concerned me was having higher CPU temps with the lid closed.

    I read a thread a few days ago that said there is no CPU temp change between lid closed and lid opened. And after doing some of my own testing I now believe that information is FALSE.

    I use smcFanControl to control fan speed and monitor CPU temp.

    Before using smcFantControl to boost my fan speed to constantly run at 3,400RPM, my CPU temp was 10-20 degrees (celsius) higher, on average.

    As for the lid open vs. closed theory....

    - 24" external monitor
    - wireless keyboard/mouse
    - Targus Chill Mat
    Apps running: Safari, Adium, iTunes, Mail, inDesign, illustrator
    Fan speed: set at constant 3,400 RPM's
    Time powered on with all apps running: 4 hours
    Ambient room temp: 72 degrees Fahrenheit

    Lid closed
    CPU Temp: 64 degrees Celsius

    Lid open:
    CPU temp: 43 degrees Celsius

    Take this info as you will. I just know that I will be using my MBP with the lid open from now on.
  2. adamk77 macrumors 6502

    Jan 6, 2008
    It's my understanding that the MBP draws in air from the vents around the keyboard. So having it closed will definitely make it run hotter.

    Also, can someone who use it with it closed explain to me why you woudln't want the extra real estate of an extra monitor?
  3. gr8tfly macrumors 603


    Oct 29, 2006
    ~119W 34N
    Although the cooling is slightly different, I did run lid open/closed tests on my 2.33GHz MBP C2D. It was warmer, closed, but only a couple of degrees. The test was done while running Handbrake.
  4. BENI macrumors regular


    Jun 27, 2009
    I can confirm this.

    I have used insomniax (freeware app that keeps Mb Pro awake when lid is closed) while ripping a DVD which is pretty intensive on the CPU.
    When I looked again after about 1/2 hour it was around 83C compared a usual 60/65C withe the lid open.

    when I am just running normally - browsing, word proccessing, mailing etc... even all of these at once! (wow!!! I know scary eh? :eek: haha) - it runs around 37C to 48C depending on the ambient air temp, which actually makes a hell of a difference! way more than you might think. on a really hot day I could run a 60 doing nothing! just from the air temp.

    in fact I would say that keeping your room cool could even be more affective than fan controllers or heat absorbent stands. I am running at 38/40C right now on a CPU of 5 to 20%. is that cool? or average? or hot?
    it would be nice to know where I stand. all I know at the moment is in relation to my one macbook pro.
  5. vant macrumors 65816

    Jul 1, 2009
    Try flipping it upside down and do some tests.

    Heat rises, so when you have the vent facing down it's inefficient.

    When you close the lid, you are effectively insulating the macbook. That whole space between the two areas is sealed.
  6. abijnk macrumors 68040


    Oct 15, 2007
    Los Angeles, CA
    Sure, no room.

  7. xlii macrumors 68000


    Sep 19, 2006
    Millis, Massachusetts
    From the look of the apple logo on in the picture the exhaust vent on the laptop is pointed down. Since hot air rises it would be better to have the vent pointed up when putting it in the stand. I don't have a stand so I haven't tested that theory... just an observation.
  8. maflynn Moderator


    Staff Member

    May 3, 2009
    I noticed that with the lid closed my mbp runs hotter then open. So much so I rarely do this
  9. adamk77 macrumors 6502

    Jan 6, 2008
    I have my MBP set up exactly like yours, except my lid is open and the monitor is higher up so that the laptop's LCD doesn't get in the way of the screen.

  10. sn0warmy thread starter macrumors 6502a


    Mar 26, 2009
    Denver, CO
    I'd say sub 40C is pretty cool for these laptops. When I pull mine out of it's case in the morning and turn it on after it's been powered off overnight and in a room with a set temp of 65F, the CPU temp is 31-35C and the aluminum casing is cool to the touch.

    I hope I didn't deceive in posting that picture. My MBP sits right side up. I found that picture online to demonstrate the stand I WANTED to get. But after this testing, I will be staying away from it.

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