Apple power mac g5 User Manual

							
166 Power Mac G5 Take Apart

Part Location
Procedure
Lay the computer so that the front panel is facing down.
Remove the black rubber cap that covers the power button LED.
Using a flatblade jeweler’s screwdriver, pry up the metal C-ring that secures the power 
button board.
1.
2.
3. 
						

							
Power Mac G5 Take Apart 167

Lift up and remove the power button board.
Remove the metal activation ring that lies below the power button board.
4.
5. 
						

							
168 Power Mac G5 Take Apart
Remove the power button from the enclosure.6. 
						

							
 Service Source
© 2005 Apple Computer, Inc. All rights reserved.
Troubleshooting
Power Mac G5 
						

							
Power Mac G5 Troubleshooting 171

General Information
Liquid Cooling System (LCS)
The Power Mac G5 (June 2004 Dual 2.5 GHz/Early 2005 Dual 2.7 GHz) configurations use a liquid 
cooling system (LCS) to manage the temperature in the computer. The liquid cooling system is 
sealed and is designed to be opened only by an Apple Authorized Service Provider (AASP).
To ensure proper safety and handling of the LCS system, please read the following information.
General Safety Information
The LCS cooling system fluid is predominantly water (80% or greater) with a mixture of corrosion 
inhibitors, antifreeze, and bacterial growth preventatives. In normal use in a non-leaking LCS 
there are no special handling considerations. However, if a leak in the system is suspected or 
discovered and the computer is plugged in, remove power to the computer by pulling power 
plug.
Nitrile or rubber glove should be worn when handling an LCS module that is leaking or 
suspected to be leaking. Evidence of leaks would include corrosion around fittings in the LCS 
coolant system, a light green or red liquid present, or a slick or slimy feel when handling the part. 
For leaks or spills, wipe up the fluid using rags, paper towels, or other suitable materials. Dispose 
of all cleaning materials according to local laws and regulations (Refer to laws and regulations 
pertaining to disposal of Antifreeze). Do not combine used coolant with any other chemical.
Place the failed LCS module (leaking or not) in the packaging that the replacement module came 
in. Follow the packaging instructions included with the replacement module. Failure to follow the 
instructions could damage your equipment and void warranty coverage.
Safety Guidelines
Below is a summary of first aid measures for exposure to the liquid. For complete instructions 
refer to the Material Safety Data Sheets (MSDS) for the liquid. The Safety Data Sheets can be 
found at http://www.apple.com/environment/resources/msds.html.
Eyes: Immediately flush with plenty of water. If wearing contact lenses, after initial flushing, 
remove contact lenses and continue to flush for 15 minutes. Have eyes examined by a 
medical professional if irritation persists. 
						

							
172 Power Mac G5 Troubleshooting

Skin: Wash skin with running water. Remove contaminated clothing. The recommended 
flushing is 15 minutes if pain or irritation occurs. Seek medical attention if irritation or 
redness develops.
Ingestion: Ingestion of this product, while unlikely to occur in its containment, may cause 
irritation of the mouth and throat, gastric upset, stomach ache, cramps, nausea and vomiting. 
If the product is swallowed, CALL PHYSICIAN OR POISON CONTROL CENTER FOR MOST 
CURRENT INFORMATION. If professional advice is not available, do not induce vomiting. 
Contaminated individuals should drink milk, egg whites, or large quantities of water. Never 
induce vomiting or give diluents (milk or water) to someone who is unconscious, having 
convulsions, or unable to swallow.
DDR Memory
In the Power Mac G5, DIMMs must be installed in pairs of equal size and speed. Use PC2700 
DDR-SDRAM for 4-DIMM-slot computers and PC3200 DDR-SDRAM for 8-DIMM-slot computers. 
Memory from older Macintosh computers is not compatible. Do not try to install non-DDR 
memory as it will not fit in the DIMM slots and could cause damage.
Important: Power Mac G5 (June 2004/Early 2005) computers support only 184-pin, 2.5 volt, 
DDR400-compliant (PC3200) DRAM DIMMs with a maximum of 4 GB or 8 GB depending on the 
configuration. 
Results of Mixing PC2100, PC2700, and PC3200 RAM
The table below describes what happens if you install PC2100, PC2700, or PC3200 memory in 
either a 4-DIMM-slot or 8-DIMM-slot Power Mac G5 computer. 
Four-DIMM-Slot Systems
When only PC2100 DIMMs are installedThe computer makes three single tones 
instead of the startup sound. The LED on the 
front of the computer flashes three times, and 
the computer does not startup.
When a mix of PC2100, PC2700, or PC 3200 
DIMMs is installed
The computer starts up normally, but neither 
the computer nor Apple System Profiler 
recognizes the PC2100 memory.
When only PC3200 DIMMs are installed in the 
slots
The computer starts up normally and behaves 
as though PC2700 DIMMs are installed.
When no memory is installed or memory is 
not installed correctly
The computer does not make a normal startup 
sound. Instead, there is a single tone, and the 
computer’s front LED flashes about once every 
5 seconds. 
						

							
Power Mac G5 Troubleshooting 173

Eight-DIMM-Slot Systems
When only PC2100 DIMMs are installedThe computer makes three single tones 
instead of the startup sound. The LED on the 
front of the computer flashes three times, and 
the computer does not startup.
When a mix of PC2100, PC2700, or PC 3200 
DIMMs is installed
The computer starts up normally, but neither 
the computer nor Apple System Profiler 
recognizes the PC2100 memory.
When no memory is installed or memory is 
not installed correctly
The computer does not make a normal startup 
sound. Instead, there is a single tone, and the 
computer’s front LED flashes about once every 
5 seconds.
PCI and AGP Cards
The Power Mac G5 computer has four expansion card slots, three of which accommodate 
Peripheral Component Interconnect (PCI) cards and one that accepts an advanced graphics port 
(AGP) video card. AGP cards and PCI cards have different connectors, so you cannot insert a PCI 
card into the AGP slot.
Note: Maximum power consumption for all four expansion slots (the three PCI expansion cards 
and the AGP card) should not exceed 90 watts ( W ). 
AGP Slot 1PCI Slot 2
PCI Slot 3PCI Slot 4 
						

							
174 Power Mac G5 Troubleshooting

AGP Cards
The AGP video card, installed in slot 1, contains the graphics processor unit (GPU) and provides 
the computer’s display ports. Slot 1 is designed specifically to accept AGP cards.
Note: When certain high-end video cards are installed in the AGP slot, they block the adjacent 
PCI/PCI-X slot (slot 2). As a result, you can install PCI/PCI-X cards in slots 3 and 4 but not in slot 2. 
For specific card information, see the video card table in the “Video” topic in the Basics chapter.
The Power Mac G5 (June 2004/Early 2005) models have the accelerated graphics port (AGP 8x 
Pro) bus. It’s an enhanced PCI bus with extra functionality to burst texture data and graphics 
across the port up to 8 times faster than a 66 MHz PCI port. The computer comes with a graphics 
card installed in the AGP 8x Pro slot and has either an ADC and DVI-I connector or dual DVI-I 
connectors. (See the “Video” topic in the Basics chapter.) The AGP bus is 1.5 V only and is not 
backward compatible. Older AGP cards will not work in these models.
PCI Cards
The remaining three expansion slots, labeled 2, 3, and 4, accommodate PCI cards up to 12 inches 
long. Depending on the Power Mac G5 model, you can install either PCI or PCI-X cards. 
Note: To determine if a Power Mac G5 computer can accommodate PCI-X cards, check the 
number of DIMM slots on the logic board. Computers with four DIMM slots have 33 MHz PCI slots 
and can’t use PCI-X cards; computers with eight DIMM slots can accommodate 100 and 133 MHz 
PCI-X cards. See the chart below.
Card type PCI slot Card speed
PCI* slots 2, 3, and 4 64-bit, 33 MHz
PCI-X slots 2 and 364-bit, 100 MHz 
PCI-Xslot 464-bit, 133 MHz
*The PCI slots can accommodate mixed-voltage (5.0 V, 12 V, or 3.3 V ) cards but only at 3.3 V 
signaling, with 32-bit or 64-bit data widths and a 33 MHz frequency. You can add a 66 MHz card 
to a 33 MHz PCI slot if the card can operate at the lower 33 MHz rate.
Warning: Installing a PCI card that functions only at 66 MHz in a 33 MHz slot could damage the 
computer. However, cards that run at both 66 MHz and 33 MHz may be installed. Check with the 
card’s manufacturer to see if a 66 MHz card also works at 33 MHz. 
						

							
Power Mac G5 Troubleshooting 175

Block Diagram
The architecture of the Power Mac G5 computer is based on the PowerPC G5 microprocessor and 
two custom ICs: the U3 memory controller/bus bridge and the K2 I/O controller.
1.5 GbpsSerial ATA bus
10/100/1000Ethernet port
Optical audio out S/PDIF
AirPort antenna port
333/400 MHzDDR memorybus
800/900/1000 MHzbuses
Optical audio in S/PDIF
FireWire 400 port (front)
16-bit3.2 GBpsHyperTransport
8-bit1.6 GBpsHyperTransport
33 MHzPCIbus
8X AGP-Pro slot2.1 GBps
PCI-X slots
PMU99powercontroller
BootROM
Modem slot
I2S
USB 2.0 port  (front)480 Mbps
USB 2.0 port (rear)480 Mbps
USB 2.0 port (rear)480 Mbps
DIMM slots
Internal hard driveconnectors
FireWire 400 port (rear)
FireWire 800 port (rear)
Main logic board
ATA/100 bus
12 Mbps USB
12 MbpsUSB
1.5 GbpsSerial ATA bus
Internal opticaldrive connectorInternalspeaker
AirPort ExtremeCard slot
U3memorycontrollerand PCIbus bridge
K2I/O deviceand diskcontroller
Headphone jack
Analog line-out
Analog line-in
FireWirePHY
Audiocircuitry
Bluetooth
PCI USBcontroller
Processor moduleProcessor module
64-bit PowerPC G5microprocessor
100 MHz
100 MHz
133 MHz
PCI-Xbridge
32-bit out32-bit in32-bit in32-bit out
Bluetooth antenna port
64-bit PowerPC G5microprocessor 
						

							
176 Power Mac G5 Troubleshooting

Thermal Calibration
To ensure proper fan and temperature control in the Power Mac G5, you must run Apple Service 
Diagnostic whenever you replace a processor or logic board with a new processor or logic board. 
You must also run the diagnostic if you re-install the same processor but in a different connector 
from the one in which it was originally installed. Apple Service Diagnostic for Power Mac G5 is 
available as a download from http://www.info.apple.com/discimages/.
Note: The calibration process of Apple Service Diagnostic requires a controlled environment to 
ensure accurate ambient temperature readings. Computers under test must have the transparent 
air deflector installed and the door sensor switch must be operable. Units under test should also 
be located away from heating and air conditioning ventilation systems and the fan exhaust of 
other machines. Ambient temperature should not go above 77 degrees Fahrenheit or 25 degrees 
Centigrade.
Resetting the PMU on the Logic Board
The PMU (Power Management Unit) is a microcontroller chip that controls all power functions for 
this computer. The PMU is a computer within a computer. Its function is to: 
tell the computer to turn on, turn off, sleep, wake, idle, etc.
manage system resets from various commands.
maintain parameter RAM (PRAM).
manage the real-time clock.
Important: Be very careful when handling the logic board. The PMU is very sensitive and 
touching the circuitry on the logic board can cause the PMU to crash. If the PMU crashes and is 
not reset, the battery life goes from about five years to about two days.
Note: For the location of the PMU reset button, see “Logic Board Diagram” in the Views chapter.
Many system problems can be resolved by resetting the PMU chip. When you have a computer 
that fails to power up, follow this procedure before replacing any modules: 
Disconnect the power cord and check the battery in the battery holder. The battery should 
read 3.3 to 3.7 volts. If the battery is bad, replace it, wait ten seconds, and then proceed to 
step 2. If the battery is good, go directly to step 2.
Press the PMU reset button once and then proceed to step 3. Do not press the PMU reset 
button a second time because it could crash the PMU chip.
Wait ten seconds before connecting the power cord and powering on the computer. If the 
computer does not power on, there is something else wrong with it; refer to the “Startup 
Failures” section of “Symptom Charts” in this chapter.
Note:  The above procedure resets the computer’s PRAM. After resetting the PMU, be sure to 
reset the time, date, and other system parameter settings.
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