Computer running hot?

It has been about a week since I upgraded my 17” MacBook Pro to Mac OS X 10.7 Lion. While some of the Finder changes have taken a bit of time to become accustomed to, I am enjoying Lion.

However, my computer has not enjoyed it completely. I noticed that it has been running about 50 degrees warmer than usual. Normally, the CPU temperature had been about 115 degrees. That had climbed to around 155. My first thought was perhaps I had a run away application, but my checks of Activity Monitor did not show any abnormal activity.


I did some research on the Internet and I noted a few other people are having this problem. While some users were suggesting increasing the fan speed, particularly on older computers, my computer is barely a year old.

It is time for some real troubleshooting. There are many things that can be done to identify and fix a computer problem. One of my favorite ones is to see if the problem exists when a new or test user account is added. This is accomplished in Apple menu > System Preferences > System > Users & Groups.


To use this tool, you must first unlock it. Notice the lock in the bottom left corner. When you click it, you will be asked for an administrator password. Set up a new user and be sure to allow this user to administer the computer.

Then go to the Apple menu and choose Log Out. At the next screen you will need to choose your test user and enter the password. The computer will do a partial restart. When it is running, see if your computer is still misbehaving.

In this case, nothing had changed, but I learned several things. First, I now know the problem is not being caused by a login item or a process running in the background. I have not ruled out a problem with the System software. I also have not ruled out a hardware problem.

There are several other things that I want to try before taking in any drastic measures. First I will reset the System Management Controller or SMC. Instructions can be found here. The following are items that are controlled by the SMC:

  • Responding to presses of the power button
  • Responding to display lid opening and closing on portable Macs
  • Battery management
  • Thermal management
  • The SMS (Sudden Motion Sensor)
  • Ambient light sensing
  • Keyboard backlighting
  • Status Indicator Light (SIL) management
  • Battery status indicator lights
  • Selecting an external (instead of internal) video source for some iMac displays
Unfortunately, the reset did not solve my problem.

The next thing I tried was to zap the PRAM. This is a bit of Apple “magic.” All sort of things are stored in Parameter Random Access Memory . They include:
  • Status of AppleTalk
  • Serial Port Configuration and Port definition
  • Alarm clock setting
  • Application font
  • Serial printer location
  • Autokey rate
  • Autokey delay
  • Speaker volume
  • Attention (beep) sound
  • Double-click time
  • Caret blink time (insertion point rate)
  • Mouse scaling (mouse speed)
  • Startup disk
  • Menu blink count
  • Monitor depth
  • 32-bit addressing
  • Virtual memory
  • RAM disk
  • Disk cache
You can find full instructions here.

Things are a bit better. My computer is not back to its normal 115 degrees, but at 135 degrees, it is running quite a bit cooler. I plan to keep an eye on it and seriously consider doing a “nuke and pave.” This is a time-consuming process. I will begin by making a clone of my hard drive to an external drive. Then I will need to make a rescue disk for Lion since Apple will not begin selling USB stick drives for this process for at least a month. After erasing my hard drive, I will install the operating system and do more testing. If the problem persists, it will be time to take my computer to the Apple Store for diagnosis by one of the Geniuses.

When the problem has been resolved I will then install all of my software from disk images, downloads and CDs. This is a long process and it will probably take me several days to get everything back to “normal.” While I don’t plan on using my Time Machine backup as a part of the restore process, I will be transferring my documents, music, pictures etc. back to my computer since data files usually are not a part of software problems.

Wish me luck! Maybe my computer will magically fix itself overnight!

-- Pat