The System Management Controller (SMC) is an internal subsystem introduced by Apple Inc. with the introduction of their new Intel processor based machines in 2006. It takes over the functions of the SMU[1]. Apple has released updates for this system in order to address power or sleep issues in several recent models [2].
Overview
The SMC controls power flow and fan speed, like the SMU before it. The main objective is to keep the machine running normally with a minimum of noise. It also enables enforcement of the Mac OS X End User License, allowing it to identify when it is running on non-Apple hardware.[3] The SMC should not normally need to be reset at all. Doing so however can be useful in troubleshooting certain issues.
- Failure to turn on
- Failure to recognize internal AirPort Extreme card
- Failure to recognize internal Bluetooth Module
- Failure to recognize attached devices (Firewire, USB, etc.)
- Unexpected power off (i.e., sudden unexpected loss of power, not system shutdown)
- Failure to wake from sleep or unexpected sleep (note this can also be caused by operating system corruption)
- Failure to recognize keyboard and trackpad
This is due to the fact the SMC may become corrupted over time and not respond properly to certain requests. This sort of corruption can be triggered by a power surge.
Current SMC Updates
| Shipping Version | Updated Version | |
|---|---|---|
| iMac Early 2006 | ? | 1.1f5 |
| Mac Mini Early 2006 | ? | 1.3f4 |
| MacBook Any | ? | 1.4f12 |
| MacBook Pro 15-inch | ? | 1.2f10 |
| MacBook Pro 17-inch | ? | 1.5f10 |
| Mac Pro 2 or 4 Cores | ? | 1.7f10 |
| Mac Pro 8 Cores | ? | 1.15f3 |