The parameter random access memory (PRAM) and the System Management Controller (SMC) control the MAC system many hardware modules, when a hardware module is invalid, the performance is unable to boot, the battery failure and so on, this time needs to reset SMC, below is the detailed operation procedure.
The steps for SMC are complex, and each device type is different, such as a MacBook with a removable battery:
1. Shutdown, unplug the power cord
2. Remove the battery
3. Hold down the power button for 5 seconds without releasing
4. Reload the battery
5. Plug in the power cord
6. Boot
Second, no removable battery of the MacBook:
1. Shutdown, plug in the power cord
2. Hold down SHIFT, control, option, and power keys at the same time
3. At the same time loosen Shift, control, Option these three keys, hold down the power button until the boot
Third, for Mac Pro, intel-based IMac, intel-based Mac Mini, intel-based Xserve and other equipment:
1. Shutdown, unplug the power cord
2. Wait 15 seconds
3. Plug in the power cord again
4. Boot