MBP fans run at 6000rpm when temp. is 37C

Discussion in 'MacBook Pro' started by SoWhat.lv, Apr 2, 2010.

  1. SoWhat.lv macrumors newbie

    Apr 1, 2010

    I know this is not the first post about noisy fan problem on MacBooks, but I haven't found any working solution jet.

    My MacBook Pro almost all the time runs very loud even if it is in "choose boot disk" mode. I checked Activity Monitor when fans are loud and when they are quiet, and there is no difference, also there is no activity on hard disk.
    I also reinstalled OS X, changed thermopasta on CPU and GPU with no luck.

    But the weirdest thing is that fans are running so fast even when temperature is very low - 37 degrees.

    I feel that problem is in EFI level, this could be some EFI virus or smth like that.

    Here is screen shot from Activity monitor when fans are at 2000rpm:
    Here when 6000rpm:
  2. spinnerlys Guest


    Sep 7, 2008
    forlod bygningen
    What specific MBP model do you have and what Mac OS X version does it run?

    Have you tried resetting the SMC yet?

    Have you installed any fan control software?
  3. SoWhat.lv thread starter macrumors newbie

    Apr 1, 2010
    OS X 10.6.3

    Hardware Overview:

    Model Name: MacBook Pro
    Model Identifier: MacBookPro2,2
    Processor Name: Intel Core 2 Duo
    Processor Speed: 2.16 GHz
    Number Of Processors: 1
    Total Number Of Cores: 2
    L2 Cache: 4 MB
    Memory: 4 GB
    Bus Speed: 667 MHz
    Boot ROM Version: MBP22.00A5.B07
    SMC Version (system): 1.12f5

    Yes, I tried to reset SMC - didn't help.

    Yes, I use smcFanControl 2.2.2 to monitor temp. and RPM, and set maximum RPM limit (force fans to run slower).
  4. spinnerlys Guest


    Sep 7, 2008
    forlod bygningen
    The SMC is not reset on every start up, the RAM is.
    SMC reset instructions made by Apple found via SMC reset MacBook Pro.

    What do you mean by "set maximum RPM limit"? The maximum is 6000RPM, the minimum is 2000RPM (sometimes even less).

    PS: Consider removing your serial number from the System Profiler copy, as that may be used for other purposes, like selling stolen Macs for example.
  5. SoWhat.lv thread starter macrumors newbie

    Apr 1, 2010
    smcFanControl has a command line option for setting maximum fan speed.
    My fans work so loud that I can't use it on public place, so I set max. rpm from 6200 to 3000 or 4000 depending on CPU temperature.

    I tried to reset SMC, but it didn't help.
  6. Pax macrumors 6502a

    Dec 12, 2003
    I am confused about what you are saying. When you say your Mac is very loud do you mean
    (a) the fans are loud even at 2000 rpm
    (b) the fans are quiet at 2000 rpm, but the fans ramp up to 6000 rpm even when the CPU is cool
    (c) something else

    I also don't understand what you are saying about smcfancontrol. Are you saying you can manually control the fan speed, but the Mac won't do it automatically?

    Can you be a bit clearer about what your problem is?
  7. SoWhat.lv thread starter macrumors newbie

    Apr 1, 2010
    thanks for trying to understand me :)

    a) NO
    b) YES

    Yes, I control fan speed manually when Mac is trying to run fans at 6000RPM.

    The problem is that system switches fans to 6000RPM too soon. It should switch to 6000RPM at about 60C temp. but it switches when temp. is 37C.
  8. Pax macrumors 6502a

    Dec 12, 2003
    cool, we understand each other! I'm trying to think what your problem could be. I have written some possibilities here, there may be more. Also, some of my ideas
    - may be stupid, or
    - you may have thought of them already, or
    - both :)

    1. CPU temperature sensor reading wrong.

    This seems very unlikely, the sensor is built into the CPU. But 37 C seems very cool for a 2006 MacBook Pro at idle. I don't have much experience with them, but I thought the early Intel computers run quite hot, even with good thermal paste. Certainly my 2006 model MacBook is more like 50 - 60 C at idle - very hot.

    The way to check this one is to look at other temperatures. At idle if your CPU is at 37 C then I would expect your heatsink to be at around 30-33 C. I don't know what SMCfancontrol reports, but iStat Pro reports lots of temperatures.

    2. the GPU, not the CPU, is hot

    You said you replaced the thermal paste on the GPU. Is it possible you did this wrong? If the GPU was very hot, the fans might be coming on to keep the GPU cool, not the CPU.

    How to check - look at GPU temperature. It should be nice and cool (40 C ???? I don't know)

    3. The Mac firmware thinks the heatsink is very hot

    If the heatsink temperature sensor was broken or disconnected, maybe the firmware thinks the heatsink is very hot and the fans are speeding up because of this.

    Again, look at all the temperatures:- heatsink, GPU, CPU. If you post all your temperatures from iStat Pro we would get an idea. If you did this with the CPU idle, and the CPU working hard, we could see if anything was wrong in the hardware.

    4. The fan feedback controller has failed

    I think the fans have a speed sensor wire which reports back to the firmware. If this was broken the firmware would not know how fast the fans were going. But you say SMCfancontrol reports the speed correctly, so this can't be the problem.

    5. A problem in the firmware

    I don't think there are any firmware viruses in existence (I could be wrong). Your firmware could be corrupt but that seems quite unlikely. I don't know much about the firmware and the SMC, maybe someone else reading this knows.

    I hate to say it, but since you have taken your Mac apart and taken the heatsink off, the most likely answer is that something is wrong with the hardware - the way you put it back together (Occam's razor). I expect you did the work to a high standard, but it is always possible to forget something when you do a complex job like this.

    If you post the temperature of all your components at idle and under full load maybe we will have more ideas.
  9. SoWhat.lv thread starter macrumors newbie

    Apr 1, 2010
    Here are results from idle temp.
    It is so low, because fans are working on very high rpm. And I bought the best thermalpaste I could get Arctic Cooling MX-3 :)

    and here is almost full load

    and here is normal idle temp. at 2500rpm:
  10. Pax macrumors 6502a

    Dec 12, 2003
    OK I understand, your CPU seems very cool because your fans are running so fast.

    Just one comment, your "almost full load" picture shows only one CPU core at maximum, not both. There is 42% idle which is nearly one whole core. A good way to get both cores to maximum is to open 2 x terminal windows and type yes > /dev/null into each one. That starts 2x endless CPU loops. What does iStat Pro show then?

    I looked hard at your temperatures, they look OK but there are a few funny things...

    1. Memory Bank 1 seems very hot. Hotter than the CPU, the GPU and the heatsinks? That seems unlikely. Memory does not generate very much heat. Where is all that heat coming from?

    2. The GPU heatsink seems to be hotter than the GPU, and hotter than the CPU heatsink. That seems very strange. Where is that extra heat coming from? I would expect to see the GPU heatsink perhaps 5 C cooler than the GPU, maybe similar to the CPU heatsink.

    It looks like you have done a good job on the CPU thermal paste, the CPU and heatsink temperatures are different by 15 C at about 50% CPU load. That seems OK, mine is 20-25 C at 100% load, with the standard Apple thermal paste. (unibody MBP 13")

    I think maybe something is funny with your GPU cooling, and possibly your memory cooling. I don't know if it is a sensor, or your thermal paste, or something funny with the heatsinks/fans. I do not know if this is enough to cause your fan problems, but it can't help. I can imagine it is possible that the fan control algorithm has got confused by the GPU heatsink being hotter than the GPU, or the memory being very hot.

    Can you work your GPU hard, eg with a game or (maybe?) a DVD to see how hot the GPU and its heatsink get.

    ???????????????? Just some ideas
  11. SoWhat.lv thread starter macrumors newbie

    Apr 1, 2010
    Full CPU load

    I will search for some dvd, wait a bit for GPU full load.
  12. Pax macrumors 6502a

    Dec 12, 2003
    OK, so your CPU and CPU heatsink temperatures are different by 24 C, that's the same as mine so seems OK.

    Same picture
    - your memory always seems to be at 48 C, whatever the Mac is doing. Strange. My uMBP does not report the memory temperature, so I don't know what to expect.
    - your GPU heatsink is hotter than your GPU & hotter than GPU heatsink.


    I'm not sure a DVD will be enough to work the GPU hard, you might have to get a free game. I used Flightgear (free flight simulator) from http://www.flightgear.org/ to really work my computer hard. It takes a while to download and set up. You might have to run it for 10-20 minutes to get things really cooking! PS it only uses one CPU core, so if you want to work GPU & both CPU cores hard you will have to run 1 x yes > /dev/null as well.

    I am knocking off for a beer in a few minutes, maybe we can carry on tomorrow (I am on GMT+1 time).

    can anyone else with a similar model MBP report temperatures in the same way? Can anyone who's an expert on GPU & memory temperatures add their expertise?
  13. SoWhat.lv thread starter macrumors newbie

    Apr 1, 2010
    okay, lets continue tomorrow :) I will try to find something that uses GPU a lot.
    Have a nice evening! thanks for help!
  14. SoWhat.lv thread starter macrumors newbie

    Apr 1, 2010
    I did a Hardware test and found following error: 4SNS/1/40000000: Th1H

    Google says that this is a temperature sensor error.
    Because sometimes fans run normally I will not be able to detect broken sensor easily. Maybe someone knows which sensor is mentioned in code?

    It probably isn't one which iStat shows, because they all are showing normal temp.
  15. Pax macrumors 6502a

    Dec 12, 2003
    I googled "Th1H sensor heatsink"

    and got a lot of stuff, I haven't read it carefully but it looks like it could be Heat Pipe 2 which might be the GPU heatsink (I am guessing)???

    Also I found this thread which talks about fans at 6000 rpm when sensors have failed:-

    This all ties in with the idea that the GPU heatsink sensor is reading funny. Maybe you need to look at that sensor? It might have a broken wire or not be connected to the heasink properly, or unplugged from the logic board???
  16. SoWhat.lv thread starter macrumors newbie

    Apr 1, 2010
    can you tell me which of these sensors is a heatsink sensor? To what it should be connected?

    Is this the correct sensor?
  17. Pax macrumors 6502a

    Dec 12, 2003
    I don't know what the inside of the MBP looks like.

    We think it is the sensor nearest the GPU, so what I suggest you do is:
    - look through the iFixit guides and find a good photo of the logic board
    - work out where the GPU is on the logic board
    - work out which heatsink it is attached to
    - (remember, the logic board goes into the computer upside down)
    - have a good look at that sensor

    There are some more photos here, but I still don't understand how it plugs into the logic board. Maybe if you had a GOOD look at these photos close up you could see how it works.

  18. SoWhat.lv thread starter macrumors newbie

    Apr 1, 2010
    I opened my Mac, found GPU Heatsink sensor, disconnected it, iStat showed a line instead of temperature, so I am sure that this was GPU heatsink sensor. Connected it back, now iStat shows temperature again, all sensor wiring looks good, but my fans are still at 6000rpm.

    Maybe problem is in Mem Bank A1? Where this sensor should be? I am sure, that it isn't on RAM, because ram plates are much colder than CPU and GPU.

    Edit: Probably problem is somewhere else, because RPM jumps up before Mem Bank A1 has reached 40 C
  19. Pax macrumors 6502a

    Dec 12, 2003
    Did you Google and read the links??? There is lots of useful stuff there
    This one
    tells me several things
    (1) "Temp (Th1H) - Heat Pipe 2 Heatsink (test #1)"
    (2) a broken thermal sensor caused his problems

    I would guess sensor H stands for Heat Pipe, D might be Die (CPU or GPU) and P which is proximity.

    - does your sensor still report GPU heatsink hotter than GPU & CPU? If so that still seems to indicate a problem with that sensor
    - what does Hardware test say now that you have unplugged & reconnected the sensor?
    - if you unplug the sensor again and run Hardware Test what does it report? A different failed sensor, the same one, nothing?
    - does Hardware Test report back any more info about the failed sensor? eg its location
  20. SoWhat.lv thread starter macrumors newbie

    Apr 1, 2010
    I have red all results from Google yesterday, but I didn't find anything useful :( They all end with suggestion to take Mac to the dealer, but no solution to the problem.

    Here are current temperatures from opened Mac [​IMG]
    As you see, heatsink temperatures are normal.

    After reconnecting sensor, HW test still shows same error.

    That was a very good idea to disconnect sensor and run hardware test - now I know that Th1H isn't the sensor on heat pipe, because when I disconnected it, HW test reported error TG0H.
    After disconnecting sensor which is sticked to aluminium under fan, I got back old error, so probably this is the broken sensor (I hope).

    My HW test from OS X 10.4.8 install disk 1 doesn't tell any additional info, maybe newer versions reports something more.
  21. Pax macrumors 6502a

    Dec 12, 2003
    OK good, that was worth doing. So I guess the sensor coding is
    T for thermal
    G for GPU
    0 is number zero
    H is heatsink.
    Or something like that.

    kind of confirms that Th1H is a heatsink sensor not associated with any particular component.

    Cool. So it sounds like you have a cheap broken sensor on the fan. And you don't need a new logic board!

    It seems that as soon as the Mac gets a broken sensor it puts the fan on 6000 rpm as a fail safe mechanism. That is nice to know.

    Sounds like something quite easy to fix. Let me know how you get on.

    Also, I checked out the temperatures on my 2006 Macbook which has a similar design to yours. Memory Bank A1 was at about 47 C with the CPU at about 55 C and the fan at 2000 rpm. So the memory gets quite hot. I guess your Mem Bank A1 temperature is probably OK.
  22. SoWhat.lv thread starter macrumors newbie

    Apr 1, 2010
    Oh My God, I fixed it!!!!

    I have one identical MacBook with broken Motherboard, so I just replaced sensor from there and look what I've got

    I can't belive it was so easy! :)
    Thank you! I couldn't do it without you!!!
  23. Pax macrumors 6502a

    Dec 12, 2003
    :) That's great, I'm really pleased

    It just shows you can fix a lot of stuff with a bit of thinking. And you don't always need to send it back to Apple.

    It's also nice to know that these forums do work sometimes - they actually save people money. Much more fun than reading people saying "OMG when are Apple gonna release i5 MacBook Pros"

    I've learned a lot - thanks for that. If my MBP ever starts overheating I will have some good ideas about what to do.
  24. Pax macrumors 6502a

    Dec 12, 2003
    It's very interesting to know that there are 9 or 10 sensors all over the inside of your Mac, and iStat doesn't report all of them.

    Lots of people on these forums worry a lot about their Macs overheating. But it's pretty clear that Apple takes heat very, very seriously, otherwise they would not spend the time & money putting so many sensors in. Also if ANY sensor fails they put the cooling system into fail safe mode ie fans at 6000 rpm.

    Another thing I noticed is that changing the thermal paste didn't make any difference to your CPU vs heatsink temperatures. Yours was 25 C and so is mine with the standard Apple paste. I am even more convinced that changing the paste makes very little difference to CPU temperatures. Apple's factory does a pretty good job. All this talk about swapping the paste to Arctic Silver or whatever is just a myth.

    It was your idea to run Hardware Test, we should have thought of that much earlier. So I don't think I helped that much.


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