Resetting the Logic Board

System Management Controller (SMC) Reset

The System Management Controller (SMC) is a chip on the logic board that controls all power functions for the computer. If the computer is experiencing any power issue, resetting the SMC may resolve it. The SMC controls several functions, including:

  • Telling the computer when to turn on, turn off, sleep, wake, idle, and so forth
  • Handling system resets from various commands
  • Controlling the fans

It is also recommended that the SMC be reset after a logic board, ambient board, or ambient board cable is replaced as part of a repair.

Note that resetting the SMC does not reset the PRAM. Resetting the SMC will not resolve issues in which the computer is unresponsiveā€”in these situations, restarting the computer will generally suffice. If the computer isn't responding, perform these steps one at a time, in the following order, until the issue has been resolved:

  1. Force Quit (Option-Command-Escape)
  2. Restart (Control-Command-Power)
  3. Force Shut Down (press the power button for 10 seconds)

Resetting the SMC can resolve some computer issues such as not starting up, not displaying video, sleep issues, fan noise issues, and so forth. If the computer still exhibits these types of issues after you've restarted the computer, try resetting the SMC by removing AC power:

  1. From the Apple menu, choose Shut Down (or if the computer is not responding, hold the power button until it turns off).
  2. Unplug the AC power cord.
  3. Wait at least 15 seconds.
  4. Plug the power cord back in, making sure the power button is not being pressed at the time.
  5. Press the power button to start up the computer.

Note: Unlike the logic board in earlier Mac Pro models, the logic board in the Mac Pro (Early 2008) computer does not include an SMC reset switch.

Real Time Clock (RTC) Reset

The Real Time Clock (RTC) is a chip on the logic board that controls the date and time functions of the computer. If the computer is experiencing an issue booting, resetting the RTC may resolve it. Follow these steps to reset the RTC:

  1. From the Apple menu, choose Shut Down (or if the computer is not responding, hold the power button until it turns off).
  2. Unplug the AC power cord.
  3. Remove the battery for at least 20 seconds. You may need to remove a PCI Express card to have access to the battery.

System Reset

Mac Pro (Early 2008) has a system reset switch on the logic board that may be used to restart the system while it is powered up. This switch can be used to determine if a computer that won't consistently boot from a cold start has power supply issues. Follow these steps to reset the system:

  1. With the computer powered up, press the SYS_RST switch located in the upper right-hand corner of the logic board. To press the switch, use the nylon probe tool (Apple part number 922-5065).
  2. If the computer boots after you press the SYS_RST switch, try shutting the computer off and restarting by pressing the front power button. If the computer restarts when you press the SYS_RST switch but not from a cold start, the power supply may need to be replaced.
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Responses

  • balbo
    How to reset apple macpro?
    9 years ago
  • florian
    How to reset the power board on the macbook pro?
    9 years ago
  • paul
    How to reset the logic board of macbook pro 15?
    9 years ago
  • MIRANDA
    How to restart macbook pro 17" with logic board problem?
    9 years ago
  • eerik laine
    Can i reset imacg5 with command control power button?
    9 years ago
  • cara
    Where is apple part number on g5 logic board?
    8 years ago
  • Irmina Pagnotto
    What does the logic board on a mac control?
    8 years ago
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    Which chip in the macbook controls the clock?
    8 years ago
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    What kind of logic board does the 2008 13 inch macbook have?
    8 years ago
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    8 years ago
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    How to restart a macbook pro computer if it shut off?
    8 years ago
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    Where to find logic board part number macbook pro 13?
    8 years ago
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    8 years ago
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    Where is smc internal reset switch mac pro?
    8 years ago
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    How to reset the logic borad mac book?
    8 years ago
  • Pandora
    How to fix Mac if computer isn't responding?
    8 years ago
  • janet
    How is macbook pro logic board powered?
    8 years ago
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    Why would the clock on the macbook pro reset?
    8 years ago
  • novella
    What is the function of the logic board in a macbook Pro?
    8 years ago
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    How to repair macbook pro 15 logic board wont shut down?
    8 years ago
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    Can you switch the logic board from a 17in mac to a 15 in mac?
    8 years ago
  • KADEN KERR
    What is rtc in mac pro?
    8 years ago
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    How do i know if logic board needs replacement mac pro?
    8 years ago
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    How to switch macbook on from logic board?
    8 years ago
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    How to reset smc on 2008 mac pro?
    8 years ago
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    3 years ago
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    2 years ago
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    8 months ago

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