Apple mac pro User Manual

							Mac Pro Troubleshooting — General Information 141
DIMMs for Mac Pro must fit these specifications:
667 MHz, FB-DIMMs• 
72-bit wide, 240-pin modules• 
36 devices maximum per DIMM• 
Error-correcting code (ECC)• 
Important: For proper operation of Mac Pro computers, Apple recommends using only Apple-
approved Mac Pro FB-DIMMs. Refer to GSX for Apple FB-DIMMs service part numbers.
PCI Express Cards
The Mac Pro logic board includes one double-wide PCI Express graphics slot and three PCI 
Express expansion slots, for a total of four slots. The computer comes with a graphics card 
installed in slot 1. You can install additional PCI Express graphics and expansion cards in the 
remaining three PCI Express expansion slots.
Important: Combined maximum power consumption for all four PCI Express slots must not 
exceed 300 W.
Slot 1: Double-wide
PCI Express graphics
(graphics card installed) Slots 2–4: PCI Express
Note: Port 2 of the ATI Radeon X1900 XT graphics card is compatible with the Apple DVI-to-video 
adapter. See KnowledgeBase article 304910.
Internal Cabling Matrix
The table on the next page lists all Mac Pro internal cables that connect to the logic board and 
are not part of a larger subassembly. Following the table is a map of the logic board connector 
locations, which are listed in column 5 of the table. 
						

							Mac Pro Troubleshooting — General Information 142
Cable, Connector and Signal MatrixCABLE DESCRIPTION
Service PN
LENGTH (mm)
LENGTH (in)
MLB CONN LOCATION
MLB CONN LABEL
MLB CONN DESCRIPTION
CONNECTOR 2 DESCRIPTION
CONNECTOR 3 DESCRIPTION
CONNECTOR 4 DESCRIPTION
CONNECTOR 5 DESCRIPTION
POWER / SIGNALS CARRIED
HDD SATA
P art of 922-7682
450
17.7
B -1
SATA
36-pin high-densit y
7-pin flat to HDD 1
7-pin flat to HDD 2
7-pin flat to HDD 3
7-pin flat to HDD 4
Serial A TA signals to/from all four HDDs and main logic board
HDD P ower
Part of 922-7682
442
17.4
A -1
HDD_PWR
8-pin (2X4)
15-pin flat to HDD 1
15-pin flat to HDD 2
15-pin flat to HDD 3
15-pin flat to HDD 4
DC power to all four HDDs from main logic board
HDD Thermal Sensor
922-7730
610
24.0
A-2
HDD_SNS
4-pin flat (4X1)
7-pin flat to sensor bd underneath HDD 1
7-pin flat to sensor bd underneath HDD 2
7-pin flat to sensor bd underneath HDD 3
7-pin flat to sensor bd underneath HDD 4
Thermal sensor signals from sensors in all HDD ba ys to main logic board
Optical Drive Power
922-7684
559
22.0
B-1
ODD_PWR
4-pin square (2X2)
standard 4-pin (4x1) to upper ODD
standard 4-pin (4x1) to lower ODD
DC power to both optical driv es from main logic board
Optical Drive IDE
922-7686
586
23.1
D-1
OPTICAL
40-pin standard IDE (20X2)
Standard 40-pin IDE for lower ODD
Standard 40-pin IDE for upper ODD
IDE signals to/from all optical drives and main logic board
Power Supply PS#1
922-7687
1170
46.1
K -6
none
Large 10-pin (5X2)
Large 10-pin (5x2) from PS labeled PS#1
DC power to main logic board from power supply
Power Supply PS#2
922-7688
605
23.8
J-1
none
Large 10-pin (5X2)
Large 10-pin (5x2) from PS labeled PS#2
DC power to main logic board From power supply
Power Supply PS#3
922-7689
370
14.6
B -1
none
Large 12-pin (6X2)
Large 12-pin (6x2) from PS labeled PS#3
DC power to main logic board From power supply
Power Supply Control PS#4
922-7685
1160
45.7
K -6
none
Medium 10-pin (5X2)
Large 10-pin (5x2) from PS labeled PS#4
Power supply control signals to/from main logic board
Front P anel Board P ower 
922-7690
860
33.9
K-7
FP_MISC
Medium 8-pin (4X2)
Medium 8-pin (4x2) on top of FP bd
Power , power LED , power button, and control signals to the front panel board from the main logic board
Front Panel Board A udio
922-7692
865
34.1
J-9
FP AUDIO
Small sidew ays 5-pin (5X1)
Small sidew ays 5-pin on top of FP bd
A udio signals to the front panel board from the main logic board
Front P anel Board FireWire-800
922-7691
695
27.4
K-7
FP FWB
9-pin sidew ays standard FW800
9-pin sidew ays standard FW800 on bottom of FP bd
Standard FW800 9-pin to 9-pin cable to front panel board from main logic board
Front P anel Board USB
922-7693
150
5.9
C-2
FP_USB
Small 7-pin rt angle (7X1)
Small 7-pin rt angle in middle of FP bd
USB 2.0 power and data to front panel board from main logic board
Intak e Ambient T emperature Sensor
922-7731
400
15.7
B-2
ODD_SNS
Small 4-pin (4X1)
Small 7-pin on  thermal sensor bd inside top of ODD ba y
Thermal sensor signals from ODD bay ambient temp sensor to main logic board 
						

							Mac Pro Troubleshooting — General Information 143
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 computer does not 
require running Apple Service Diagnostic for thermal calibration. 
						

							Mac Pro Troubleshooting — General Information 14 4
Block Diagram
The architecture of the Mac Pro is based on two dual-core Intel Xeon processors, the North 
Bridge memory controller and the South Bridge I/O controller, as shown in the simplified block 
diagram below. 
						

							Mac Pro Troubleshooting — General Information 145
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. There are two ways to reset the 
SMC on Mac Pro.
You can use the SMC reset switch:
From the Apple menu, choose Shut Down (or if the computer is not responding, hold the 1. 
power button until it turns off ).
Press the SMC_RST switch, which is located to the right and slightly below the row of 2.  
diagnostic LEDs. (See the LED diagram in the following “Diagnostic LEDs” section.) To press 
the switch, use the nylon probe tool (Apple part number 922-5065).
Press the power button to start up the computer.3. 
Or, you can reset 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.  
						

							Mac Pro Troubleshooting — General Information 146
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 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 DIMM 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 next 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 Troubleshooting — General Information 14 7
Diagnostic LEDs
The Mac Pro logic board includes a set of LEDs to help service providers troubleshoot the 
computer. The LEDs are located toward the rear of the logic board, under the memory cage, next 
to PCI card slot 1. You can view these LEDs by removing the computer’s side access panel and 
looking through the memory cage to the logic board below. LEDs 2, 3, 4, and 5 are normally off 
and will automatically illuminate if an error occurs. To read LEDs 1, 6, 7, and 8, 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 Troubleshooting — General Information 14 8
Use the following table to interpret the LEDs.
LocationNameColorNominalPress DIAG_
LED button 
to display
Indicates
Led 1Trickle PwrYellowOnYe sPower supply 
is providing 
trickle power
Led 2CPU B ErrorRedOffNoCPU B halts 
on an IERR 
(instruction 
error)
Led 3CPU A ErrorRedOffNoCPU A halts 
on an IERR 
(instruction 
error)
Led 4CPU B OTRedOffNoCPU B is over 
temperature
Led 5CPU A OTRedOffNoCPU A is over 
temperature
Led 6GPU PresentGreenOnYe sEFI has 
configured 
the graphics 
card
Led 7Power OnGreenOnYe sAll power 
rails are 
functioning
Led 8EFI DoneGreenOnYe sEFI is done 
loading
Note: There is a position on the logic board next to LED 1 for a SLEEP LED that does not have 
any LED installed. This is normal; the LED was used only in development. To determine if a Mac 
Pro computer is in sleep mode, watch the power LED on the front of the computer. It will slowly 
change brightness levels if the computer is sleeping.
LED 1 Trickle Power
Normally on when DIAG_LED button is pressed. 
If LED 1 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 Troubleshooting — General Information 149
LED 2 CPU B (Lower Processor) Error 
LED 3 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 pressing the SMC_RST switch. • 
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 4 CPU B (Lower Processor) Overtemp
LED 5 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. If both LEDs are solidly on at 
power up, the power supply cables may be improperly seated.
Troubleshooting: 
Verify proper heat sink 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. 
						

							Mac Pro Troubleshooting — General Information 150
Replace the processor associated with the corresponding LED.• 
LED 6 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 (if the card • 
requires one). 
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. • 
LED 7 Power On
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 8 EFI Good
Normally on when DIAG_LED button is pressed. Takes approximately 5 seconds after power up.
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 7 Power On LED is on. • 
Check that LEDs 2, 3, 4, and 5 are off. • 
Try removing any added hardware. • 
Try removing any added DIMMs. •