smcFanControl

A compiled copy of version 2.4 can be found at the author's site or on this site:

You can unzip the file with unzip smcfancontrol_2_4.zip. In the directory where you unzipped the file you will see the following files and directories.

$ ls -l | cut -f1,8- -d" "
total
-rw-r--r--  10906 Aug 21  2012 F.A.Q.rtf
-rw-r--r--  17987 Oct  1  2006 LICENSE
drwxrwxr-x    136 Aug 21  2012 __MACOSX
drwxr-xr-x    102 Aug 21  2012 smcFanControl.app

You can copy or move the smcFanControl.app directory under the Applications directory, if you wish to have the utility in the directory where other applications are commonly stored.

When you run the GUI for the software by double-clicking on smcFanControl, which is what you will see in the OS X Finder when you navigate to the smcFanControl.app directory, to start the utility, you will be prompted for a password for an account with administrator access to the system. When you provide the password, you may see the following alert:

Alert!

smcFanControl has not been tested on this machine
yet, but it should run if you follow the instructions.

If you choose to continue, please make you have no
other FanControl-software running. Otherwise please
quit, deinstall the other software, restart your
machine and rerun smcFanControl!

If you click on the Continue button, you will then be prompted to answer whether you wish to check for updates on startup.

If a new version of the software is available, you will be given an opportunity to install the update.

When the application runs you won't have a window open, but if you look at the top of the screen you should see a temperature displayed with a fan speed below it, e.g. 63°C and 2005rpm as shown below where the information is displayed above a Safari browser window.

The smcFanControl preferences window will allow you to adjust the minimum speed for fans.

From the Menubar drop-down list you can change the displayed information from "Temperature & Fans" to any of the following:

Temperature & Fanspeed (multiline)
Temperature & Fanspeed (singleline)
Icon only
Temperature only
Fanspeed only

However, if you just want a utility that you can run from a command line interface (CLI), aka a shell prompt, such as you can get with the Terminal app found in Applications/Utilities, you can use the smc program which you can find beneath the Contents/Resources directory where the smcFanControl.app directory was placed. To see fan speeds, use smc -f.

$ /Applications/smcFanControl.app/Contents/Resources/smc
Apple System Management Control (SMC) tool 0.01
Usage:
/Applications/smcFanControl.app/Contents/Resources/smc [options]
    -f         : fan info decoded
    -h         : help
    -k    : key to manipulate
    -l         : list all keys and values
    -r         : read the value of a key
    -w  : write the specified value to a key
    -v         : version

$ /Applications/smcFanControl.app/Contents/Resources/smc -f
Total fans in system: 2

Fan #0:
    Fan ID       : Left side  
    Actual speed : 1997
    Minimum speed: 2000
    Maximum speed: 6200
    Safe speed   : 0
    Target speed : 2000
    Mode         : auto

Fan #1:
    Fan ID       : Right side 
    Actual speed : 2001
    Minimum speed: 2000
    Maximum speed: 6200
    Safe speed   : 0
    Target speed : 2000
    Mode         : auto
$