Confused which Power Mac G5 you have, not sure which is listed in an ebay auction, looking to ask the right questions to a seller?
First a couple basics on the Power Mac G5, it comes in many different variation based on the 64 bit PowerPC 970 chip  known as the G5.

A few details they all have....

   1. One bay for a DVD-R/CDR-W Superdrive, or DVD/CDR-W Combo drive
   2. 2 harddisk bays for SATA harddrives, ATA or IDE drives are not supported in the G5
   3. ram installed in pairs on dual processor machines (be sure to check which machine you have so you get the correct ram)
   4. optional airport extreme slot 802.11g, not as the G4 towers that use the original 802.11b cards.(PCI-X machines only)
   5. bluetooth is optional on all machines with module version 1.1 except for the dual core machines offering version 2.0
   6. all have 10/100/1000 ethernet ports onboard
   7. backup PRAM battery is the same on all models apple P/N 922-4028
   8. All 4 memory slot G5 have only PCI slots not as many believe PCI-X slots be aware of this when searching for expansion cards

The serial number on PowerMac G5 towers is found inside the machine after opening the access panel, it's on the aluminum casing right below the Processor heatsink(s). Serial Numbers starting with (RM) are remanufactured machines indicating they were originally sold as factory refurbished.

The first 4 generations all have the same port layout and are PCI-X machines, only with the introduction of the dual core and dual dual core (QUAD) the port layout changed and also they switched to PCI-Express. The main difference between the port layout of PCI-X vs PCI-Express G5 towers are the USB and audio out port found on PCI-Express G5's fronts and the second ethernet port on the PCI-Express G5 machines rear port cluster.


The first 4 generations came with a choice of Super or Combo drives, dual layer drives were not yet available and if featured are a later upgrade.

1st Generation Power Mac G5 PCI-X (Omega or Q37)(shipped 06/2003)

    * single G5 1.6 Ghz with a max ram of 4 gig(PC2700)(PCI ONLY NOT PCI-X)
    * single G5 1.8 Ghz with a max ram of 8 gig(PC3200)
    * dual G5 1.8 & 2.0 Ghz with a max ram of 8 gig(PC3200)
    * shipped with SATA harddrives of 80 gigs and up, you can upgrade these at will with any SATA harddrive
    * 8x AGP Pro
    * 2 firewire 400 ports, 1 firewire 800 port, 2 USB 2.0 ports
    * shipped with 10.2.7 thru 10.3

2nd Generation Power Mac G5 PCI-X (Niagra or Q77)(shipped 06/2004)

    * dual G5 1.8 Ghz with max ram of only 4gig (PC3200)(PCI ONLY NOT PCI-X)
    * dual G5 2.0 & 2.5 with max ram of 8gig (PC3200)
    * shipped with SATA harddrives of 80 gigs and up, you can upgrade these at will with any SATA harddrive
    * 8x AGP Pro
    * 2 firewire 400 ports, 1 firewire 800 port, 2 USB 2.0 ports
    * shipped with 10.3.4 thru 10.3.7

3rd Generation Power Mac G5 PCI-X (shipped 10/2004)

    * single G5 1.8 Ghz with a max ram of only 4 gig (PC3200)(PCI ONLY NOT PCI-X)
    * 8x AGP Pro
    * 2 firewire 400 ports, 1 firewire 800 port, 2 USB 2.0 ports
    * shipped with 10.3.5 thru 10.4

4th Generation Power Mac G5 PCI-X (Q87)(04/2005)

    * dual G5 2.0 Ghz with a max ram of only 4 gig (PC3200)(PCI ONLY NOT PCI-X)
    * dual G5 2.3 and 2.7 Ghz with a max ram of 8 gig (PC3200)
    * shipped with SATA harddrives of 160 gigs and up, you can upgrade these at will with any SATA harddrive
    * 8x AGP Pro
    * 2 firewire 400 ports, 1 firewire 800 port, 2 USB 2.0 ports
    * shipped with 10.4

5th Generation Power Mac G5 PCI-EXPRESS (Cypher)(DUAL CORE)(10/2005)

    * dual core G5 2.0 or 2.3 Ghz with a max ram of 16 gig (PC4200)
    * quad core G5 2.5 Ghz with a max ram of 16 gig (PC4200)
    * dual layer superdrives(16x )
    * 128 mb video ram standard on the 2.0 Ghz, 256 mb video ram on the 2.3 and 2.5
    * expansion slots are one 16x, one 8x and two 4x PCI Express
    * dual ethernet ports
    * 2 firewire 400 ports, 1 firewire 800 port, 4 USB 2.0 ports
    * shipped with 10.4.2 thru 10.4.4

Basiclly when looking for a G5 Tower be aware of the different configurations that were available, configurations with only 4 gig of possible memory usually sell for substantially less at auction then the versions that have a max of 8 gig.

Upgrading the harddrives in the tower is very easy but you are limited to 2 bays in a G5 tower. Putting in faster then the stock 7200 rpm harddrives with such drives like the Western Digital 10000rpm raptors can significantly increase performance. Some aftermarket vendors sell kits to install more harddrives using a PCI card and the space in the PCI area to mount the harddrives. I have not seen or tested any of these configuration but think some sort of external harddrive solution would make more sense then filling up the PCI slots with harddrives.

Video card upgrades are possible, remember that running the Apple 30 inch Cinema display requires a capable card check my other guide for more on that click here.

Some people have bench tested different configurations against each other, from my personal experience running Tiger 10.4.x RAM in excess of 2GB is what is needed to overcome the marginal amounts they originally shipped with (512mb). Also the latest PCI-Express dual core & quad G5's are almost all faster then any of the previous models, mostly because of the faster ram and system architecture. Tests have shown the fastest G5 dual, the 2.7 Ghz to be only marginally faster then a dual core 2.3 Ghz. The dual core 2.3 Ghz only lost in some of the straight CPU tests while beating the dual 2.7 Ghz in most other everyday use for this model.

Going back to the guide I mentioned above about graphics cards for these machines. They could be the deciding factor in which machine is perfect for a certain user.

PCI-X graphics card with dual dvi link have been largely discontinued but finding a machine with such a card in place might be the cheapest alternative to be able to run 2 displays that need dual dvi link support, like 2 Apple 30 inch Cinema Displays.

On the newer PCI-Express dual core & quad machines the built to order cards are NOT available from apple in their apple store, so upgrading is not an option. Some people sell modified PC versions of these cards which until now is the only option for PCI-Express dual core & quad owners to upgrade their video card. People looking to run Aperature on PCI-Express G5's be adviced that the only card that really makes Aperature useable is the 7800 or Quadra FX card, some owners of QUADs with 6600 cards have sold their machines on ebay to then order new machines with the 7800 or Quadra FX card because Apple will NOT sell you a built to order card after shipping the original machine. A google search will reveal more on the 6600 card and problems with running Aperature. November 2006 and the first aftermarket card for PCI-Express G5's is available. Sold thru ATI's website the Radeon X1900 G5 Mac Edition should be an interesting upgrade for owners of 6600 cards that have not been able to locate a 7800 card.

Please Rate this Guide, your rating makes this guide mean something. If you believe I should correct or edit my guide in any way feedback is always welcome.