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 does not require running Apple Service Diagnostic for thermal calibration. 
						

							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 commands• 
Controlling the fans• 
It is also recommended that the SMC be reset after a logic board, ambient board, or ambient 
board cable is replaced as part of a repair.
Note that resetting the SMC does not reset the PRAM. Resetting the SMC will not resolve issues in 
which the computer is unresponsive—in these situations, restarting the computer will generally 
suffice. If the computer isn’t responding, perform these steps one at a time, in the following order, 
until the issue has been resolved:
Force Quit (Option-Command-Escape)1. 
Restart (Control-Command-Power)2.  
Force Shut Down (press the power button for 10 seconds)3. 
Resetting the SMC can resolve some computer issues such as not starting up, not displaying 
video, sleep issues, fan noise issues, and so forth. If the computer still exhibits these types of 
issues after you’ve restarted the computer, try resetting the SMC by removing AC power:
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.  
Wait at least 15 seconds.3. 
Plug the power cord back in, making sure the power button is not being pressed at the time. 4. 
Press the power button to start up the computer.5. 
Note: Unlike the logic board in earlier Mac Pro models, the logic board in the Mac Pro (Early 
2008) computer does not include an SMC reset switch. 
						

							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 least 20 seconds. You may need to remove a PCI Express card to 3. 
have access to the battery. 
System Reset
Mac Pro (Early 2008) has a system reset switch on the logic board that may be used to restart 
the system while it is powered up. This switch can be used to determine if a computer that 
won’t consistently boot from a cold start has power supply issues. Follow these steps to reset the 
system:
With the computer powered up, press the SYS_RST switch located in the upper right-hand 1. 
corner of the logic board. To press the switch, use the nylon probe tool (Apple part number 
922-5065).
If the computer boots after you press the SYS_RST switch, try shutting the computer off and 2.  
restarting by pressing the front power button. If the computer restarts when you press the 
SYS_RST switch but not from a cold start, the power supply may need to be replaced. 
Power-On Self Test: RAM and Processor Verification
A power-on self test in the computer’s ROM automatically runs whenever the computer is started 
up after being fully shut down (the test does not run if the computer is only restarted). If the test 
detects a problem, the status LED located above the power button on the front of the computer 
will flash in the following ways*: 
1 Flash: No RAM is installed or detected. Or, the quick memory test failed. An LED will light up • 
on the memory riser card next to the affected DIMM or empty DIMM slot.
3 Flashes: A RAM bank failed extended memory testing. An LED will light up on the memory • 
riser card corresponding to the affected DIMM.
Troubleshooting: Try reseating the memory DIMMs. Check memory installation instructions for 
proper installation order. Swap affected DIMM with known good DIMM.
*Note: The status LED lights up when the power button is depressed at startup. Do not count this 
light as one of the diagnostic flashes. The memory riser card diagnostic LEDs will also flash briefly 
when the computer is started up or shut down and when it goes in and out of sleep mode. This 
is normal behavior. 
						

							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 the DIAG_LED button, use the nylon probe tool (Apple part number 922-5065). 
						

							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 
temperature
Led 6CPU A OTRedOffNoCPU A is over 
temperature
Led 7GPU PresentGreenOnYe sEFI has 
configured 
the graphics 
card
Led 8Power GoodGreenOnYe sAll power 
rails are 
functioning
Led 9EFI DoneGreenOnYe sEFI is done 
loading
LED 1 Sleep
LED 2 Standby or Trickle Power
Normally on when DIAG_LED button is pressed. 
If LED 2 is not on, the symptom would be that the computer won’t power on. 
Troubleshooting: 
Check AC cord is connected to a working AC wall outlet. • 
Reseat AC Plug.• 
Check connections of power supply cables to the logic board. • 
Check power supply cable connections at power supply. • 
Replace power supply.•  
						

							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 computer booted, up press the SYS_RST switch. If this clears the CPU Error LED, • 
check for incompatible device driver software that may have been installed for added 
hardware. 
If the Error LED is still on, power down the computer and try resetting the SMC. Restart the • 
computer.
Reset the power supply by unplugging the AC cord for 10 seconds.• 
Unplug AC cord and remove any added DIMMs and PCI Express cards. If this causes the • 
LED to go off, repopulate the DIMMs and/or PCI Express cards to find the combination that 
caused the LED to come on. Overheated memory could be a possible cause for this CPU 
error LED to come on. Check fan operation.
Unplug the AC cord and remove the battery for 10 seconds. You may need to remove a PCI • 
Express card to get to the battery. Reinstall the battery and restart the computer.
Try swapping CPU A and CPU B locations. If the CPU Error LED follows the CPU, replace that • 
CPU. 
Try replacing the logic board.• 
LED 5 CPU B (Lower Processor) Overtemp
LED 6 CPU A (Upper Processor) Overtemp
Normally off. These LEDs come on if an error occurs. They do not depend on the DIAG_LED 
button being pressed. 
These two LEDs can operate in two different modes; they will either flash or stay on. If either 
LED is flashing, it may indicate an initial processor over-temperature condition. If either LED is 
solidly on, it may indicate a chronic processor over-temperature condition. Initial processor over-
temperature can cause symptoms such as sluggish computer performance. Chronic processor 
over-temperature can cause the computer to hang completely.
Troubleshooting: 
Verify proper heatsink installation. • 
Verify all thermal sensors are properly connected. • 
Verify all fans are operating properly, especially the front intake fan.• 
Verify power supply cables are properly seated. • 
If both overtemp LEDs come on immediately when the computer is turned on, a faulty • 
power supply could be one cause of this behavior. Replace power supply.
Try swapping CPU A and CPU B heatsink locations. If the CPU Error LED follows the CPU •  
						

							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 from connectors on the logic board. For these 
cards, if the auxiliary booster power cable is not connected between the logic board and the 
graphics card, an error message reminding about this additional power connection will be 
displayed as Mac OS X starts up.
Troubleshooting: 
Check that the graphics card is seated correctly in its PCI slot. • 
Check that the card’s auxiliary booster power cable is connected properly on both ends • 
(if the card requires one). If the cable is connected properly, try connecting it to the other, 
empty logic board booster power connector (if available) to see if the cause is related to 
this connector. If the card and LED operate properly when connected to the other power 
connector, check EFI and SMC firmware versions and update them if necessary. See “Mac 
Pro Firmware Updates” in this section for more information. Only then should you consider 
replacing the logic board.
Verify power supply cables are properly seated• .
Try the graphics card in a different PCI slot.• 
Try a different graphics card. • 
If an error message about graphic card booster power connection is displayed, check that • 
the appropriate booster power cable is firmly connected between the logic board and the 
graphics card.
Replace the logic board. • 
Replace the PS3 power supply cable. (• Note: This cable supplies power to the PCI slots.)
LED 8 Power Good
Normally on when DIAG_LED button is pressed. 
If this LED is on, it indicates the power supply is functioning. 
Troubleshooting: 
Check that the power cables to the logic board  are properly attached. • 
Check the cable connections at the power supply. • 
Check for any signs of an obvious electrical short, e.g. metal screws or PCI card slot cover • 
loose inside computer touching the logic board.
LED 9 EFI Good
Normally on when DIAG_LED button is pressed. Takes approximately 5 seconds after power up. 
						

							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. Each of the LEDs will 
light if it detects an issue with the corresponding installed DIMM. These LEDs will also flash briefly 
when the computer is started up or shut down and when it goes in and out of sleep mode. This 
is normal behavior.
Troubleshooting: 
Shutdown and restart the computer. • 
Verify EFI and SMC firmware versions and update them if necessary.  See “• Mac Pro Firmware 
Updates” in this section for more information.
Reseat the memory riser card associated with the failure LED.  If the failure LED persists, • 
continue with the next step.
Swap upper and lower memory riser cards A and B.  If the symptoms follow the riser card, • 
continue with the next step.  If the failure LED remains associated with the same memory 
riser card slot, consider a possible connection issue with the logic board.  Replace the logic 
board in this case.
Reseat the appropriate DIMM corresponding to the failure LED.  If the issue persists, continue • 
with the next step.
Check memory installation instructions for proper installation order. • 
Swap affected DIMM with known good DIMM.• 
Try moving DIMM to another slot (within the same bank of two) to see if the failure LED • 
follows the DIMM. If so, replace DIMM with known good DIMM. If the failure LED persists, 
replace the memory riser card associated with the failure LED.
Video Card Diagnostic LEDs
T_Fault LED
Normally off, this LED lights up if the graphics chip gets too hot.
Troubleshooting: 
Verify that the video card heatsink and fan are not clogged with dust. Carefully blow out any • 
dust as necessary.
Check that the front fan is working. • 
Try re-seating the card in the PCI Slot. • 
Make sure the card’s auxiliary booster power cable is connected (if there is one). • 
Re-boot the computer. •  
						

							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 power on, the computer’s logic board requires “trickle” power. If the system fails to power on, 
first 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 2 indicates the presence of trickle power required by the logic board to begin the 
startup process. 
LED 2 should be yellow when the DIAG_ LED button is pressed, indicating that trickle voltage is 
present.
Verify Power Supply Is Providing Power 
Diagnostic LED 8 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 8 should be green when the DIAG_ LED button is pressed, indicating that the main power is 
OK and within regulation.
If diagnostic LED 5 and LED 6 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 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. 
						

							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 update if necessary 
before replacing any hardware components in the Mac Pro (Early 2008).
The following lists describe the type of symptoms that may be resolved by updating the EFI and 
SMC firmware in the Mac Pro (Early 2008).
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 Riser Card Diagnostic LEDs & CPU Overtemp LEDs to • 
illuminate solidly
Unit does not restart after changing configuration in Expansion Slot Utility• 
Please follow the steps outlined in KnowledgeBase article 303364, “About Firmware Updates for 
Intel-based Macs,” to perform an EFI and/or SMC firmware update. Information about firmware 
versions for Intel Macs can be found in KnowledgeBase article 303880, “Mac OS X: Firmware 
Updates for Intel-based Macs.”