System management unit
Encyclopedia
The System Management Unit (SMU) is an advanced internal subsystem introduced in late 2004 with the iMac G5
and Power Mac G5
series computers. It manages the functions previously governed by the PMU
(Power Management Unit) as well as additional cooling functions.
, which communicates the necessary adjustments back to the SMU. The SMU makes the changes, slowing down or speeding up fans as necessary.
Resetting the SMU may fix certain problems during troubleshooting
.
IMac G5
The iMac G5 was a series of desktop Macintosh computers designed and built by Apple Inc. using the PowerPC chip architecture. It was the last line of iMac computers that used a PowerPC chip, making it the last of the iMacs that could run Mac OS 9 applications. In August 2004, the iMac design was...
and Power Mac G5
Power Mac G5
The Power Mac G5 is Apple's marketing name for models of the Power Macintosh that contains the IBM PowerPC G5 CPU. The professional-grade computer was the most powerful in Apple's lineup when it was introduced, widely hailed as the first 64-bit PC, and was touted by Apple as the fastest personal...
series computers. It manages the functions previously governed by the PMU
Power Management Unit
The Power Management Unit is a microcontroller that governs power functions of digital platforms. This microchip has many similar components to the average computer, including firmware and software, memory, a CPU, input/output functions, timers to measure intervals of time, as well as analog to...
(Power Management Unit) as well as additional cooling functions.
Overview
The SMU manages thermal and power conditions to optimize the power and airflow while keeping audible noise to a minimum. Power consumption and temperature are monitored by the operating systemOperating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
, which communicates the necessary adjustments back to the SMU. The SMU makes the changes, slowing down or speeding up fans as necessary.
Resetting the SMU may fix certain problems during troubleshooting
Troubleshooting
Troubleshooting is a form of problem solving, often applied to repair failed products or processes. It is a logical, systematic search for the source of a problem so that it can be solved, and so the product or process can be made operational again. Troubleshooting is needed to develop and...
.