Here something from the "Apple Technician Guide";
Mac Pro Firmware Updates
Firmware is software written into memory circuits, such as flash memory, that will hold the software code indefinitely, 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 firmware updates update the Boot ROM, and SMC updates update the System Management Controller firmware. 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 firmware versions and update if necessary before replacing any hardware components.
The following lists describe the type of symptoms that may be resolved by updating the EFI and SMC firmware.
Symptoms that may be resolved by updating EFI firmware:
• Cannot eject media (various conditions)
• No video on start up
• Blue system failure screens in Windows XP/Vista
• Not waking or sleeping when expected
• Bad media taking too long to eject (including holding mouse button down at startup taking minutes to eject)
Symptoms that may be resolved by updating SMC firmware:
• Fan related behavior (excessive speed or noise)
• Loud audible clicking from some fans
• Thermal shut down or warnings
• Diagnostics reporting failures
• Sleep/wake issues
• Intermittent shut down
• SMC causes bad/missing ambient sensor to cause the computer to go to sleep
• Hangs, black screen on restart from Windows
• Quick power cycle causes Memory Processor Board Diagnostic LEDs and CPU Overtemp LEDs to illuminate solidly
Important: Since the SMC firmware is stored on both the backplane board and processor board, it is important that the version of SMC firmware is the same on both boards.
And this is what Apple say (
Restoring firmware with a Firmware Restoration CD
To restore your computer's firmware, you must first create a CD using the disk image named "FirmwareRestorationCD.dmg" by following these steps:
- Open Disk Utility (located at /Applications/Utilities).
- Click the Burn icon or select the "Burn…" menu item from the Images menu.
- Navigate to where FirmwareRestorationCD.dmg is located, and click the Burn button.
- Insert a blank recordable CD.
- Click the Burn button to create the Firmware Restoration CD. The files are burned to the disc.
Next, use the Firmware Restoration CD to restore your Firmware:
- Make sure that the computer you are trying to restore is plugged into an AC outlet.
- Turn on the computer and continue holding the Power button. The sleep LED will blink rapidly, then slowly, then rapidly (3 quick blinks, 3 slow blinks, 3 quick blinks).
On Macs that don't have a sleep LED, tones are used instead. Hold down the power button until you hear 3 long tones, then 3 short tones, then 3 long tones.
On Macs that use a tray-load optical drive, the tray will open to allow the Restoration CD to be inserted.
- Insert the Firmware Restoration CD while the lights are blinking or tones sounding, then release the Power button. A long tone is played once the recovery process has started.
A progress bar appears beneath an Apple logo on a gray screen. The progress bar indicates the firmware is being updated. Do not disconnect power, shut down, or restart the computer during the update or you will need to start the restoration process again beginning with step 6.
The computer will restart automatically after the firmware is updated.
Just what I found here and now.
/Per
