Apple mac pro early 2008 User Manual

Mac Pro (Early 2008) Troubleshooting — General Information 151
Cable Connector Locations
Use the diagram below to find the location of the internal cable connectors on the logic board.
A        B       C        D        E        F        G       H        J   \
      K
A 
       B       C        D        E        F        G       H        J   \
      K
1 2 3 4 5 6 7 8 9
12 3 4 5 6 7 8 9
Thermal Calibration
Unlike in earlier Power Mac G5 computers, replacing a processor in a Mac Pro (Early 2008) 
computer...

Mac Pro (Early 2008) Troubleshooting — General Information 15 2
Resetting the Logic Board
System Management Controller (SMC) Reset
The System Management Controller (SMC) is a chip on the logic board that controls all power 
functions for the computer. If the computer is experiencing any power issue, resetting the SMC 
may resolve it. The SMC controls several functions, including:
Telling the computer when to turn on, turn off, sleep, wake, idle, and so forth• 
Handling system resets from various...

Mac Pro (Early 2008) Troubleshooting — General Information 15 3
Real Time Clock (RTC) Reset
The Real Time Clock (RTC) is a chip on the logic board that controls the date and time functions 
of the computer. If the computer is experiencing an issue booting, resetting the RTC may resolve 
it. Follow these steps to reset the RTC:
From the Apple menu, choose Shut Down (or if the computer is not responding, hold the 1. 
power button until it turns off ).
Unplug the AC power cord.2.  
Remove the battery for at...

Mac Pro (Early 2008) Troubleshooting — General Information 154
Diagnostic LEDs
Logic Board Diagnostic LEDs
The Mac Pro (Early 2008) logic board includes a set of LEDs to help service providers troubleshoot 
the computer. The LEDs are located on the logic board between the two DIMM riser card 
connectors. LEDs 3, 4, 5, and 6 are normally off and will automatically illuminate if an error occurs. 
To read LEDs 1, 2, 7, 8, and 9, you must press the DIAG_LED button, which is adjacent to the LEDs. 
To press...

Mac Pro (Early 2008) Troubleshooting — General Information 15 5
Use the following table to interpret the LEDs.
LocationNameColorNominalPress DIAG_
LED button 
to display
Indicates
Led 1SleepRedOff; on when 
computer is 
in sleep mode
Ye sSleep mode
Led 2Standby 
( Trickle Pwr)
YellowOnYe sPower supply 
is providing 
trickle power
Led 3CPU B ErrorRedOffNoCPU B halts 
on an IERR 
(instruction 
error)
Led 4CPU A ErrorRedOffNoCPU A halts 
on an IERR 
(instruction 
error)
Led 5CPU B OTRedOffNoCPU B is over...

Mac Pro (Early 2008) Troubleshooting — General Information 156
LED 3 CPU B (Lower Processor) Error 
LED 4 CPU A (Upper Processor) Error
Normally off. These LEDs come on if an error occurs or if the BootROM is corrupted. They do not 
depend on the DIAG_LED button being pressed.
Related symptoms include no video or the computer is hung up. If the BootROM is corrupted, 
the optical drive tray should eject, prompting for the insertion of a recovery disc to restore the 
BootROM.
Troubleshooting: 
With the...

Mac Pro (Early 2008) Troubleshooting — General Information 15 7
heatsink, replace that CPU heatsink.
Try swapping CPU A and CPU B locations. If the CPU Error LED follows the CPU, replace that • 
CPU.
LED 7 GPU Present
Normally on when DIAG_LED button is pressed. 
If this LED is on, it indicates there is a graphics card installed and recognized by the computer. 
It does not indicate that the graphics card is fully functional. Some graphics cards require 
additional power to function, which is available...

Mac Pro (Early 2008) Troubleshooting — General Information 15 8
If this LED is on, it indicates that the computer has completed the on board Extensible Firmware 
Interface (EFI) operations and the operating system is now in control. 
Troubleshooting: 
Check that LED 8 Power Good LED is on. • 
Check that LEDs 3, 4, 5, and 6 are off. • 
Try removing any added hardware. • 
Try removing any added DIMMs. • 
Memory Riser Card Diagnostic LEDs
Both of the memory riser cards include diagnostic LEDs for each DIMM....

Mac Pro (Early 2008) Troubleshooting — General Information 15 9
Try a different video card. • 
Replace the video card.• 
Ext_Power LED
Normally off, this LED lights up if the auxiliary power isn’t being supplied.
Troubleshooting: 
Make sure the card’s auxiliary booster power cable is connected (if there is one). • 
Check connections from the power supply to the logic board. • 
Try a different auxiliary power cable. • 
Try a different video card. • 
Replace the video card.• 
Power Supply Verification 
To...

Mac Pro (Early 2008) Troubleshooting — General Information 160
EFI and SMC firmware is stored on the Mac Pro (Early 2008) logic board. 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...