Apple power mac g5 early 2005 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...

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...

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...

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...

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...

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...