Specifications

Power Mac G5 (Late 2005) Troubleshooting — General Information 137
In the Power Mac G5 (Late 2005), DIMMs must t the following specications. 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
Unbuered (registered or buered 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 specications 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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