Apple mac pro early 2008 User Manual

							Mac Pro (Early 2008) Take Apart — Power Cable Harness 141
Power Cable Harness
The power cable harness consists of the following cables:
Power supply PS1 cable• 
Power supply PS2 cable• 
Power supply PS3 cable• 
Power supply PS4 control cable• 
Front panel board power cable• 
Front panel board audio cable• 
Front panel board FireWire 800 cable• 
Tools
No tools are required for this procedure.
Preliminary Steps
Before you begin, open the computer, lay it on its side with the access side facing up, and remove 
the following:
Optical drive carrier and optical drive• s
H• ard drives and hard drive carriers in drive bays 1 and 2
PCI Express card installed in slot • 1
Any 12-inch • PCI Express cards
Processor heatsink cove• r
Front fan assembl• y
Top and bottom memory card• s
Memory cage with rear fan• 
Optical drive power cabl• e
Optical drive data cabl• e
Front panel boar• d 
						

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Part Location
Procedure
Disconnect the power cable harness connectors from the logic board. 1.  
						

							Mac Pro (Early 2008) Take Apart — Power Cable Harness 143
Using a Phillips screwdriver, remove the two mounting screws on the power supply cable 2. 
cover located at the back of the optical drive bay. 
Slide the cover toward the top of the enclosure, tilt it up until the two tabs on the cover clear 3. 
the slots in the media shelf, and remove the cover from the enclosure. 
 
Replacement Note: Replace the cover at an angle so that the tabs engage with the slots in 
the media shelf. Then lower the cover into place. 
						

							Mac Pro (Early 2008) Take Apart — Power Cable Harness 14 4
Release the four power supply cables from their hook-and-loop fasteners on the enclosure.4. 
Depress the locking latch on each cable connector and disconnect the four power supply 5. 
cables from the four connectors on the power harness cable. 
Slip the four connectors out through the opening in the media shelf, removing them one at 6. 
a time.  
						

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Untape the power harness cable from the enclosure. 7. 
Remove the power harness cable from its routing along the edge of the logic board, over the 8.  
speaker assembly, and along the bottom lip of the enclosure. 
Remove the power harness cable from the enclosure.9.  
						

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 Service Source 
Troubleshooting
Mac Pro (Early 2008) 
						

							Mac Pro (Early 2008) Troubleshooting — General Information 14 7
General Information
Memory
The Mac Pro (Early 2008) computer has two memory riser cards with a total of 8 memory slots. 
On each card, the slots are arranged as two banks of two slots each. The computer comes with 
a minimum of 2 GB of memory, installed as a pair of 1 GB FB-DIMMs. Additional pairs of 1 GB, 2 
GB, or 4 GB FB-DIMMs can be installed in the open DIMM slots, as illustrated below. Maximum 
memory is 32 GB.
DIMMs must be installed as pairs of identical size and type, from the same vendor. In the 
illustration below, like-colored DIMMs must match. 
						

							Mac Pro (Early 2008) Troubleshooting — General Information 14 8
DIMMs for Mac Pro (Early 2008) must fit these specifications:
800 MHz, DDR2, FB-DIMMs• 
72-bit wide, 240-pin modules• 
36 memory ICs maximum per DIMM• 
Error-correcting code (ECC)• 
Memory from older Macintosh computers is not compatible with Mac Pro (Early 2008). 
Important: For proper operation of Mac Pro (Early 2008) computers, Apple recommends using 
only Apple-approved Mac Pro (Early 2008) FB-DIMMs. Refer to GSX for Apple FB-DIMMs service 
part numbers.
Independent Memory Channels
Memory technology in Mac Pro (Early 2008) is based on serializing the channel from the 
memory controller hub (MCH) to the FB-DIMM module. The MCH has two independent branches 
with two channels per branch, each channel supporting up to two FB-DIMMs. Because the 
communications to each channel is independent, the memory bandwidth in Mac Pro (Early 
2008) is four times greater than in the typical parallel bus configuration used by DDR and DDR2 
memory, where the bus is shared by all DIMMs. In addition, the Mac Pro (Early 2008) serial 
channels are dual simplex, which allows both reads and writes to occur simultaneously on the 
bus.
The graphic below illustrates the memory channels used in Mac Pro (Early 2008). 
Because of this memory technology, there are some points to keep in mind when installing Mac 
Pro (Early 2008) FB-DIMMs and riser cards:
Riser A and Riser B cards are interchangeable.•  
						

							Mac Pro (Early 2008) Troubleshooting — General Information 149
DIMMs must be installed as pairs of identical size and type, from the same vendor. One pair • 
need not match another pair. (Refer to the illustration on page 147.)
On either riser card, if a DIMM is installed in position 3 or 4 without DIMMs in positions 1 • 
and 2 on that riser card,  the DIMM in position 3 or 4 will not be recognized by the system. 
DIMMs in positions 3 and 4 rely on DIMMs in positions 1 and 2 to forward information to and 
from the MCH.
For optimal performance, all four channels should be populated. For example, for a 4-GB • 
system, optimal performance would be achieved with four 1-GB DIMMs occupying slots 
1 and 2 on both riser cards, as opposed to a configuration with two 2-GB DIMMs or a 
configuration with four 1-GB DIMMs populating all slots on one riser card.
If only two DIMMs are installed in a system, one DIMM should be installed in slot 1 of each • 
riser card.
PCI Express Cards
The Mac Pro (Early 2008) 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
Internal Cabling Matrix
The table on the next page lists all Mac Pro (Early 2008) 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 3 of the table. 
						

							Mac Pro (Early 2008) Troubleshooting — General Information 150
Cable Matrix
M86 Int Cable Matrix Vertical.xlsCONDIFENTIAL - NEED T O KNOW ONLY
CABLE DESCRIPTION
Service 
PN
MLB CONN 
LOCATIONPOWER / SIGNALS CARRIED
HDD SATA
P art of 922-
8487C -1
Serial A TA signals to/from all 
four HDDs and main logic board
HDD P ower
Part of 922-
8487A -1
DC power to all four HDDs from 
main logic board
HDD Thermal Sensor922-8522A-2
Thermal sensor signals from 
sensors in all HDD ba ys to main 
logic board
Optical Drive Power922-8488B-1
DC power to both optical driv es 
from main logic board
Optical Drive IDE922-8489D-1
IDE signals to/from all optical 
drives and main logic board
Power Supply PS #1922-8500K -6
DC power to main logic board 
from power supply
Power Supply PS #2
Part of 922-
8501J-1
DC power to main logic board 
From power supply
Power Supply PS #3
Part of 922-
8501B -1
DC power to main logic board 
From power supply
Power Supply Control PS # 4922-8499K -6
Power supply control signals 
to/from main logic board
Front P anel Board P ower 922-8490K-7
Power , power LED , power 
button, and control signals to 
the front panel board from the 
main logic board
Front Panel Board A udio922-8560J-9
Audio signals to the front panel 
board from the main logic board
Front P anel Board FireWire-800922-8561K-7
Standard FW800 9-pin to 9-pin 
cable to front panel board from 
main logic board
Front P anel Board USB922-8494C-2
USB 2.0 power and data to front 
panel board from main logic 
board
Intak e Ambient T emperature 
Sensor922-8523B-2
Thermal sensor signals from 
ODD ba y ambient temp sensor 
to main logic board