User Guide
Mac Pro Troubleshooting — General Information 15 2
Power Supply Verication
To power on, the computer’s logic board requires “trickle” power. If the system fails to power on,
rst reset the SMC as described in this chapter. If the computer still doesn’t power on, follow the
procedure outlined below to determine whether the issue is related to the power supply.
Verify trickle power
Diagnostic LED 1 indicates the presence of trickle power required by the logic board to begin the
startup process.
LED 1 should be yellow when the DIAG_ LED button is pressed, indicating that trickle voltage is
present.
Verify Power Supply Is Providing Power
Diagnostic LED 7 indicates that the main power is OK and within regulation.
Plug in AC power cord, and press the power-on button on the front panel.
LED 7 should be green when the DIAG_ LED button is pressed, indicating that the main power is
OK and within regulation.
If diagnostic LED 4 and LED 5 are both solidly illuminated at power up, improperly seated power
supply cables could be one cause of this behavior. Check all power supply cable connections to
ensure they are properly seated.
Mac Pro Firmware Updates
Firmware is the name given to software that is written into memory circuits, such as ash
memory, that will hold the software code indenitely, even when power is removed from the
hardware. Firmware on Intel Mac computers is designed to be updated if necessary through a
software update.
EFI and SMC rmware is stored on the Mac Pro’s logic board. EFI rmware updates update the
Boot ROM, and SMC updates update the System Management Controller rmware. The SMC
manages fans and other environmental parameters that are independent of the Boot ROM.
Firmware symptoms can be easily mistaken for hardware issues (e.g., overheating issues, fan
noise issues, etc.). Always check both EFI and SMC rmware versions and update if necessary
before replacing any hardware components in the Mac Pro.
The following lists describe the type of symptoms that may be resolved by updating the EFI and
SMC rmware in the Mac Pro.
Symptoms that may be resolved by updating EFI rmware:
Cannot eject media (various conditions)•
No video on start up•