Apple power mac g5 late 2005 User Manual

							
Power Mac G5 (Late 2005) Take Apart — Power Supply 131
Replacement Note: To fit the power supply back into the enclosure, align the power supply so 
that it is parallel to the bottom panel and push the power supply straight back until the bus bar 
tabs snap into place. Then slide the power supply toward the back of the computer, making sure 
the power receptacle aligns with the opening in the back panel.
Note: Make sure the power supply cables do not catch on the enclosure or under the power 
supply.
Replacement Note: Be sure to replace the mushroom-head standoff after installing the power 
supply in the enclosure. 
						

							
Power Mac G5 (Late 2005) Take Apart — Air Deflector Sensor Board 132
Air Deflector Sensor Board
Tools
The only tool required for this procedure is a flatblade screwdriver. A small mirror to use in 
locating the board is optional.
Preliminary Steps
Before you begin, open the computer, lay it on its side with the access side facing up, and remove 
the following:
Front inlet fan assembly
Heatsink cover
Processor inlet frame (Dual 2.0/2.3 GHz) or Processor inlet frame (Quad)
Processor (Dual 2.0/2.3 GHz) or Processor (Quad)
Processor support bar
All graphics and PCI Express cards
AirPort Extreme/Bluetooth combo card and runway card
Rear exhaust fan assembly
PCI card guide
Speaker/fan assembly
Front panel board
PCI divider
Logic board
Power supply
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Power Mac G5 (Late 2005) Take Apart — Air Deflector Sensor Board 133
Part Location 
						

							
Power Mac G5 (Late 2005) Take Apart — Air Deflector Sensor Board 134
Procedure
Locate the air deflector sensor board inside the enclosure on the bottom right front corner 
of the frame. You may find a small mirror useful in seeing the board.
Disconnect the sensor cable from the air deflector sensor board.
Pry up the sensor board from the frame and remove the board from the enclosure. 
Note: Adhesive on the back of the board attaches the sensor board to the frame.
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 Service Source
© 2005 Apple Computer, Inc. All rights reserved.
Troubleshooting
Power Mac G5 (Late 2005) 
						

							
Power Mac G5 (Late 2005) Troubleshooting — General Information 13
General Information
DDR2 Memory
The Power Mac G5 (Late 2005) has eight DIMM slots for PC2 4200, 533 MHz, Double-Data-Rate 
2 (DDR2) SDRAM DIMMs. The slots are arranged in two banks of four slots each. Power Mac G5 
(Late 2005) computers come with a minimum of 512 MB of RAM, installed as a pair of 256 MB 
DIMMs in the two center slots. Additional DIMMs can be installed in the open DIMM slots, as 
illustrated below. 
Note: DIMMs must be installed in equal-sized pairs from the center outward.
The SDRAM DIMMs must be installedin pairs with one DIMM per bank.
DIMMs are already installed in these two slots. 
Install additional DIMMs in these two slots first. 
If slots are available, and you want to install more memory, install additional DIMMs in a similar fashion:  In pairs, one per bank, from the center outward. 
Bank 1 Bank 2  
						

							
Power Mac G5 (Late 2005) Troubleshooting — General Information 13
In the Power Mac G5 (Late 2005), DIMMs must fit the following specifications. Memory from older 
Macintosh computers is not compatible.
PC2 4200, 533 MHz, DDR2 DIMMs
240-pin module
Maximum number of memory devices on DDR2 SDRAM: 18
Nonparity
Unbuffered (registered or buffered DDR2 SDRAM cannot be used)
Either error-correcting code (ECC) or no error-correcting code (NECC) modules  
Note: Do not mix ECC and NECC memory modules within a pair. 
To identify ECC and NECC DIMMs, check the chip side of the DIMM.  ECC DIMMs include an extra 
memory device as marked below. NECC DIMMs do not have this device.
          DDR2 Memory Module with ECC        DDR2 Memory Module with NECC
PCI Express Cards
Power Mac G5 (Late 2005) computers have four expansion card slots that accommodate PCI 
Express cards. The computers come with a high-performance 16-lane (16x) PCI Express graphics 
card installed in slot 1. The card contains the graphics processor unit (GPU) and provides the 
computers’ display ports. 
You can install additional PCI Express cards in slots 2–4. Install a second card in slot 3, a third in 
slot 4, and a fourth in slot 2 to take advantage of the bus bandwidth of each slot. Before installing 
a card, however, check the specifications to make sure it can operate correctly in the Power Mac 
G5 (Late 2005).
Note: When certain high-end video cards are installed in slot 1, they block the adjacent PCI 
Express slot (slot 2). As a result, you can install PCI Express cards in slots 3 and 4 but not in slot 2. 
The maximum bus width for each PCI Express slot is marked on the card guide. Slot 4 is a 4-lane (4x) slot, slot 3 is an 8-lane (8x) slot, slot 2 is a 4-lane (4x) slot, and slot 1 is a 16-lane (16x) slot.
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Power Mac G5 (Late 2005) Troubleshooting — General Information 13
Important: Combined maximum power consumption for all four expansion slots should not 
exceed 200 W. Combined maximum video RAM for all graphics cards is 1 GB.
While all slots can accommodate PCI Express cards that have up to 16-lanes, if you install a card 
that requires a greater bandwidth than the slot provides, the card will operate at the bandwidth 
of the slot. For example, an 8x card installed in a 4x slot will operate as a 4x card. Refer to the 
following table for details.
PCI Express Slot Bus Bandwith (x) Connector (Lane)
4 4x16 lane
3 8x16 lane 
24x16 lane
116x16 lane
Thermal Calibration
To ensure proper fan and temperature control in the Power Mac G5 (Late 2005), you must run 
Apple Service Diagnostic whenever you replace a processor or logic board with a new processor 
or logic board. 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 systems and fan exhaust of other machines. 
Ambient temperature should not go above 77 degrees Fahrenheit or 25 degrees Centigrade.
Resetting the Logic Board
Some system problems can be resolved by resetting the System Management Unit (SMU) 
microcontroller chip on the Power Mac G5 (Late 2005) logic board. To reset the logic board, do 
the following:
Shut down the computer.
Unplug the computer from its power source. 
Wait two minutes.
Plug the power cord back in, and turn the computer on. 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.
You can also reset the logic board by pressing the SMU reset button on the logic board: 
Shut down the computer.
Open the computer, lay it on its side with the access side facing up, and remove the front 
inlet fan assembly.
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Power Mac G5 (Late 2005) Troubleshooting — General Information 13
Press the reset button on the logic board. 
Note: For the location of the reset button, see “Logic Board Diagram” in the Views chapter.
Replace the front inlet assembly and close the computer.
Turn on the computer.
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.
2 Flashes: Incompatible RAM types are installed or RAM installed in wrong slots.
3 Flashes: No RAM banks passed memory testing. 
4 Flashes: No good boot images are detected in the boot ROM (and/or there is a bad  
sys config block).
5 Flashes: The processor is not usable.
* 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.
Diagnostic LEDs
Power Mac G5 (Late 2005) logic boards include a set of LEDs to help service providers 
troubleshoot the computers. The LEDs are located to the left of the top bank of DIMM slots.
Top bank of DIMM slots
(Bank 1)
Edge of main logic board
LED #1
LED #2
LED #3
LED #4
LED #5
LED #6
LED #7
Use the table on the following page to interpret the LEDs.
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Power Mac G5 (Late 2005) Troubleshooting — General Information 140
Diagnostic LED Table
LED DescriptionColor When OnExpected ConditionLED “On” IndicatesThings to CheckNext Steps
No 1CPU ARedOffCPU A improperly installed
Is processor assembly seated properly? Check that mounting screws are properly tightened.
Remove processor assembly and check for damaged pins on processor connector or logic board connector. Replace processor, if necessary. Replace logic board, if necessary.
No 2Overtemp LEDRedOffCPU has gone overtemp
Check that space is allowed for fans to ventilate. Verify fans and sensors are connected.
Reseat front inlet fan. Run Thermal Calibration in Apple Service Diagnostics. Replace processor.
No 3Power OnRedOn (with air deflector open)
Main power OK and within regulation
Check connections to the power bus bar.
Check operation of the air deflector sensor. Replace power supply.
No 4Trickle PowerYellowOn (with unit plugged into AC power and air deflector open)
AC power OKCheck for AC power at the wall outlet; try another outlet.
Check operation of the air deflector sensor. Replace power supply.
No 5Open Firmware Good
GreenOn (with air deflector open)
CPU arrived at Open Firmware (logic board is OK)
Reset SMU. Check for RAM errors.Check  operation of the air deflector sensor. Replace processor. Replace logic board. 
No 6CPU BRedOffCPU B improperly installed (LED 6 only present on Quad)
Is processor assembly seated properly? Check that mounting screws are properly tightened.
Remove processor assembly and check for damaged pins on processor connector or logic board connector. Replace processor, if necessary. Replace logic board, if necessary.
No 7CheckstopRedOff (LED flashes once at startup and then goes off )
CPU hang Check RAM. Is processor assembly seated properly? Check that mounting screws are properly tightened.
Remove processor assembly and check for damaged pins on processor connector or logic board connector. Replace processor, if necessary. Replace logic board, if necessary.
Notes for LED Table
Power Mac G5 (Late 2005 Dual 2.0/2.3 GHz) logic boards include LEDs 1–5 and LED 7, but not 
LED 6. Power Mac G5 (Late 2005 Quad) logic boards include LEDs 1–7.
CPU A is located closest to the PCI Express slots; CPU B is located below CPU A (closer to the 
power supply). Make sure CPU screws are tight.
LEDs 3, 4, and 5 operate differently from the other LEDs. They remain off until you remove 
the air deflector (clear door inside the side access panel), at which point they should go 
on. If LED 3, 4, or 5 is on before you remove the air deflector, check the operation of the air 
deflector sensor. Note that the fans will run at high speed while the air deflector is removed.
LED 5 verifies that Open Firmware has loaded. To allow time for it to load, be sure to wait at 
least one minute from first power up before you check this LED.
Some logic boards have two additional LEDs: one located near the bottom edge of the logic 
board and the other to the right of the top bank of DIMM slots. These LEDs were used only 
during manufacturing and should be ignored.
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