Power Mac G5

Power Mac G5

Apple Power Mac G5
Developer	Apple Computer, Inc.
Type	Desktop
Release date	June 24, 2003
Introductory price	USD$1,999 (as of 2006)
Discontinued	August 7, 2006
CPU	1.6 – 2.7 GHz Single, Dual Processor, Dual core or Quad core PowerPC G5
Website	Power Mac Home Page

The Power Mac G5 is Apple's marketing name for models of the Power Macintosh that contains the IBM PowerPC G5 CPU. The professional-grade computer was the most powerful in Apple's lineup when it was introduced, widely hailed as the first 64-bit PC, and was touted by Apple as the fastest personal computer ever built. It was officially launched as part of Steve Jobs' keynote presentation in June 2003 at the Worldwide Developers Conference, and saw three revisions to the line before being retired in August 2006 to make way for its Intel replacement, the Mac Pro. The Power Mac G5 has an anodized aluminium chassis.

Introduction

The Power Mac G5 was introduced with three models, sharing the same physical case, but differing in features and performance. The 1.6 GHz model shipped with 256 megabytes (MB) of RAM, an 80 GB hard drive, and could hold a maximum of 4 GB of RAM, and an nVidia GeForce 5200 graphics card with 64 MB VRAM with one ADC output and one DVI output. The 1.8 and dual-processor and 2.0 GHz models shipped with 512 MB of RAM, and could employ a maximum of 8 gigabytes (GB) of RAM. The dual-processor model came with an ATI Radeon 9600 graphics card with a Radeon 9800 as an option. The physical case of the Power Mac G5 was very different and unusual compared to any other computer at that time, it had a very professional appeal to it. Many potential buyers, though, were surprised to find that the attractive case, while somewhat larger than the G4 tower it replaced, had room inside for only one optical, and two hard drives.

Steve Jobs stated during his keynote presentation that the Power Mac G5 would reach 3 GHz "within 12 months." This would never come to pass; after three years, the G5 only reached 2.7 GHz (or dual-core at 2.5 GHz) before being replaced by the Intel Xeon-based Mac Pro, which included processors with speeds of up to 3 GHz, and after three years is presently at 3.33 GHz.

During the presentation Apple also showed Virginia Tech's Mac OS X computer cluster supercomputer (a.k.a. supercluster) known as System X, consisting of 1100 Power Mac G5s operating as processing nodes. The supercomputer managed to become one of the top 5 supercomputers that year. The computer was soon dismantled and replaced with a new cluster made of an equal number of Xserve G5 rack-mounted servers, which also use the G5 chip running at 2.3 GHz.

PowerPC G5 and the IBM partnership

The inside of a Power Mac G5 Dual 1.8 GHz

The PowerPC 970FX inside a PowerMac G5.

The PowerPC G5 (called the PowerPC 970 by its manufacturer, IBM) is based upon IBM's dual-core POWER4 microprocessor. At the introduction of the Power Mac G5, Apple announced a partnership with IBM in which IBM would continue to produce PowerPC variants of their POWER processors. According to IBM's Dr. John E. Kelly, "The goal of this partnership is for Apple and IBM to come together so that Apple customers get the best of both worlds, the tremendous creativity from Apple Computers and the tremendous technology from the IBM corporation. IBM invested over $3 billion US dollars in a new lab to produce these large, 300 mm wafers." (This lab is a completely automated facility located in East Fishkill, New York, and figures heavily in IBM's microelectronics strategy above and beyond the partnership with Apple). The original PowerPC 970 has 50 million transistors and is manufactured using IBM CMOS 9S at 130 nm fabrication process. CMOS 9S is the combination of SOI, Low-k dielectric insulation, and Copper interconnect technology, which were invented at IBM research in the mid-1990s. Subsequent revisions of the "G5" processor have included IBM's PowerPC 970FX (same basic design on a 90 nm process), and the PowerPC 970MP (essentially two 970FX cores on one die). Apple refers to the dual-core PowerPC 970MP processors as either the "G5 Dual" (for single-socket, dual-core configurations), or Power Mac G5 Quad (for dual-socket, four-core configurations).

The Power Mac G5 line in 2006 consisted of three, dual-core PowerPC G5 configurations, operating at 2.0, 2.3, and a dual-processor 2.5 GHz configuration (the dual contains four cores in total, two per processor). A 2.7 GHz single-core model was also released. It contains PCI-X slots, where the newer models use PCI Express. The dual-core G5 configuration can communicate through its FSB at half its internal clock speed. Each processor in the Power Mac G5 has two unidirectional 32-bit pathways: one leading to the processor and the other from the processor. These result in a total bandwidth of up to 20 GB/s. The processor at the heart of the Power Mac G5 has a "superscalar, superpipelined" execution core that can handle up to 216 in-flight instructions, and uses a 128-bit, 162-instruction SIMD unit (AltiVec).

In addition, due to the 64-bit processor (and 42-bit MMU) the Power Mac G5 has a RAM capacity greater than the 4 GB addressable memory limit of traditional 32-bit processors. Currently, the Power Mac G5 can hold 16 GB of RAM using eight memory slots with 2 GB per stick. All modern 32-bit x86 processors since the Pentium Pro have the Physical Address Extension (PAE) feature, which permits them to use a 36-bit physical memory address to address a maximum of 2³⁶ bytes (64 gigabytes) of physical memory, while the PowerPC 970 processor is capable of addressing 2⁴² bytes (4 terabytes) of physical memory and 2⁶⁴ bytes (16 exabytes) of virtual memory. The memory in this final revision of the Power Mac G5 is Dual-Channel DDR2 PC4200, with support for ECC memory.

Product revision history

DP designates a dual-processor machine, SP designates a single-processor machine, and DC designates a dualcore-processor machine.

Component	Power Mac G5	Power Mac G5 (June 2004)	Power Mac G5 (Late 2004)	Power Mac G5 (Early 2005)	Power Mac G5 (Late 2005)
Codename	"Omega, Q37"	"Q77, Q78"	N/A	N/A	"Cypher"
Processor	SP 1.6, 1.8, DP 1.8, or DP 2.0 GHz PowerPC 970 (G5)	DP 1.8, DP 2.0, or DP 2.5 GHz PowerPC 970FX (G5)	SP 1.8 GHz PowerPC 970FX (G5)	DP 2.0, DP 2.3, or DP 2.7 GHz PowerPC 970FX (G5)	DC 2.0, DC 2.3, or DP DC "Quadcore" 2.5 GHz PowerPC 970MP (G5)
Graphics	NVIDIA GeForceFX 5200 Ultra, GeForce 6800 Ultra DDL, ATI Radeon 9600 Pro, or Radeon 9800 Pro with 64, 128, or 256 MB of DDR RAM	NVIDIA GeForceFX 5200 Ultra, GeForce 6800 GT DDL, GeForce 6800 Ultra DDL, ATI Radeon 9600 XT, or Radeon 9800 XT with 64, 128, or 256 MB of DDR RAM		NVIDIA GeForce 6800 Ultra DDL, ATI Radeon 9600, Radeon 9650, or Radeon X850 XT with 128 or 256 MB of DDR RAM	NVIDIA GeForce 6600 LE, GeForce 6600, GeForce 7800 GT, or Quadro FX 4500 with 128, 256, or 512 MB of DDR RAM
Cache	64 KB (instruction), 32 KB (data) L1, 512 KB L2				64K (instruction), 32K (data) L1, 1 MB L2 per core
Front side bus	800, 900, Dual 900 MHz, or Dual 1.0 GHz (2:1)	Dual 900 MHz, Dual 1.0, or Dual 1.25 GHz (2:1)	600 MHz (3:1)	Dual 1.0, Dual 1.15, or Dual 1.35 GHz (2:1)	1.0, 1.15, or Dual 1.25 GHz (2:1)
Memory	256MB of PC2700 DDR RAM (1.6 GHz) or 512MB of PC3200 DDR SDRAM (1.8Ghz+) Expandable up to 4 GB (1.6Ghz) or 8.0 GB (1.8Ghz+)	256MB (DP 1.8Ghz) or 512MB (DP 2.0Ghz+) of PC3200 DDR SDRAM Expandable up to 4 GB (DP 1.8Ghz) or 8.0 GB (DP 2.0Ghz+)	256MB of PC3200 DDR SDRAM Expandable up to 4 GB	512MB of PC3200 DDR SDRAM Expandable up to 4 GB (DP 2.0Ghz) or 8.0 GB (DP 2.3Ghz+)	512MB of 533 MHz PC2-4200 DDR2 SDRAM Expandable up to 16GB
Hard drive	80, 160, or 250 GB 7200 rpm			160, 250, or 400 GB 7200 rpm	160, 250, or 500 GB 7200 rpm
AirPort / Bluetooth	Optional AirPort Extreme card (802.11b/g) (external antenna) / Optional Bluetooth 1.1				Optional AirPort Extreme with Bluetooth 2.0+EDR combo card
Optical drive	4x/8x/16x/8x/32x DVD-R/CD-RW (4x SuperDrive)	8x/10x/24x/10x/32x DVD-R/CD-RW (8x SuperDrive)		16x SuperDrive (DVD+R DL/DVD±RW/CD-RW)
Expansion slots	3 - 33 MHz 64-bit PCI (1.6 GHz) 2 - 100 MHz 64-bit PCI-X and 1 - 133 MHz 64-bit PCI-X (1.8 GHz+) 1 - 8x AGP Pro (all)	3 - 33 MHz 64-bit PCI (dual 1.8 GHz) 2 - 100 MHz 64-bit PCI-X and 1 - 133 MHz 64-bit PCI-X (dual 2.0 GHz+) 1 - 8x AGP Pro (all)	3 - 33 MHz 64-bit PCI, 1 - 8x AGP Pro	3 - 33 MHz 64-bit PCI (dual 2.0 GHz) 2 - 100 MHz 64-bit PCI-X and 1 - 133 MHz 64-bit PCI-X (dual 2.3 GHz+) 1 - 8x AGP Pro (all)	2 - 4-lane, 1 - 8-lane, 1 - 16-lane PCI Express
Expansion bays	2 - Internal 3.5" Serial ATA drive bays, 1 - optical drive bay
Standard Features	3 USB 2.0, 2 Firewire 400 ports, 1 Firewire 800 port, 10/100/1000Base-T Gigabit Ethernet, Built-in Modem, Built-in mono speaker, 1 - 3.5-mm analog input jack, 1 - optical S/PDIF (Toslink) input, 2 - 3.5-mm analog output jacks, 1 - optical S/PDIF (Toslink) output			3 USB 2.0, 2 Firewire 400 ports, 1 Firewire 800 port, 10/100/1000Base-T Gigabit Ethernet, Optional Built-in Modem, Built-in mono speaker, 1 - 3.5-mm analog input jack, 1 - optical S/PDIF (Toslink) input, 2 - 3.5-mm analog output jacks, 1 - optical S/PDIF (Toslink) output	4 USB 2.0, 2 Firewire 400 ports, 1 Firewire 800 port, 2 - 10/100/1000Base-T Gigabit Ethernet Ports, Optional Apple USB Modem, Built-in mono speaker, 1 - 3.5-mm analog input jack, 1 - optical S/PDIF (Toslink) input, 2 - 3.5-mm analog output jacks, 1 - optical S/PDIF (Toslink) output
Most recent supported mac operating system	Mac OS X 10.5.8 "Leopard"
Weight	39.2 lb (17.8 kg)	44.4 lb (20.1 kg)	36 lb (16 kg)	44.4 lb (20.1 kg)	44.5–48.8 lb (20.2–22.1 kg)

• 2003 June: Initial release at speeds of SP 1.6, SP 1.8, DP 2.0 GHz.
• 2003 November: DP 1.8 replaces SP 1.8 GHz; a price reduction on SP 1.6 GHz.
• 2004 June: 90 nm DP 1.8, DP 2.0 and DP 2.5 GHz replace all previous models. The 2.5 GHz model is notable as the first major PC with liquid cooling included as stock.
• 2004 October: A new SP 1.8 reintroduced, with a slower, 600 MHz FSB (front-side bus), PCI bus, based upon the iMac G5's architecture (U3lite and Shasta chips). Apple's official name for this machine is "Power Mac G5 (Late 2004)".
• 2005 April: CPU speed increased: DP 2.5 GHz → DP 2.7 GHz (PCI-X, LC), DP 2.0 GHz → DP 2.3 GHz (PCI-X), DP 1.8 GHz → DP 2 GHz (PCI). Newly introduced features were the 16x dual-layer SuperDrives across the line and increased storage, up to 800 GB for the higher-end models. The 1.8 GHz SP was not modified.
• 2005 June: The SP 1.8 model was discontinued in the United States.
• 2005 July: The SP 1.8 model was discontinued in Europe.
• 2005 October: Shift to dual-core processors: DP 2.0 GHz → DC 2.0 GHz, DP 2.3 GHz → DC 2.3 GHz, DP 2.7 GHz → DP DC 2.5 GHz (termed a Quad Power Mac G5, with four CPU execution cores and more reliable liquid cooling), all with DDR2 memory, and PCI Express expansion in place of PCI-X. The older PCI-X, DP 2.7 GHz model remained available for a while, but the slower speed single-core models were discontinued immediately.
• 2006 August: The Power Mac is replaced by its Intel successor, the Mac Pro.

A partial list of official firmware updates

• 1 March 2006: Highly important SMU Update for G5 (Late 2004) (Apple, 2006, originally 14-Nov-2005)
• 27 September 2005: Version 5.1.5f2 (Apple, 2004)
• 17 November 2005: Version 5.1.8f7 (Apple, 2006)

Electronic audio interference problems

Early versions of dual processor G5 computers have noise problems. The first one is ground loop-based interference, which sometimes causes noise leaks into the analog audio outputs. This bug was fixed in Rev. B G5.

The second noise problem came from the 'chirping' sound, which can be triggered by fluctuations in power draw. For example, showing and hiding the Dock makes a brief chirp. Many had blamed the power supply used in the G5 as the cause, but this theory has never been confirmed. A very effective work-around is to disable the CPUs' "nap" feature using Apple's CHUD Tools, but this was not recommended by Apple. This noise problem was not fixed until the dual core generation of G5s was produced, however it did not affect the "Late2004" model (at least there have never been any reports). The power draw fluctuation was later attributed to the lack of power management features in the single-core processors. Apple eventually posted the chirping bug information on its support site.

Although the noise problems did not prevent the affected computers from working, they were problematic for audio professional and enthusiasts alike, especially for the liquid-cooled models, which had been expressly designed as mechanically quiet for discerning listeners.

Water Cooling Problems

Some 2.5GHz dual processor and all 2.7 dual processor and 2.5 Quads were cooled by a liquid cooling system (LCS) that consisted of a radiator, coolant pump, and heat exchangers that were bolted to the processors. The cooling system was made by Delphi, a former Harrison Radiator Division of General Motors. This was a bold step for Apple, and should have allowed the use of very fast processors, giving Apple an advantage in both the horsepower and reliability race, but the LCS turned out to be subject to coolant leakage. If not caught in time, the leakage can destroy the processors, logic board, and even corrode the aluminum casing itself. While leakage was sometimes detectable by drops of green coolant in or beneath the machine, in many machines the seepage is so slight that it was almost impossible to detect without dismantling the entire computer.

Apple responded with what many owners felt was a halfhearted job of standing behind the leaking G5s, extending the warranty somewhat but not providing any long term protection, making liquid-cooled G5s a dubious buy today. Anyone who finds their G5 leaking today can expect to pay approximately $1000 to have it repaired by Apple. G5 owners also complain that it is impossible to get any service information about the machines out of Apple, such as whether the coolant needs regular replacement or topping up, and if so, what to use. However DIYers claim that the problem with the Delphi LCS is with the O-Rings sealing the heat exchanger and that, if the leakage is discovered before it has damaged the electronic components, the system can be resealed with only several hours' work and $20 in parts. Later models were equipped with a Panasonic LCS which was a much more reliable system.

The LCS system fits into the case where the heat sinks would normally go, so there is no easy way to distinguish the liquid-cooled versions from the air-cooled, although most but not all of the LCS versions have a sticker inside warning about the possibility of leakage. Certain models, such as the DP 2.5 are rumored to have been available at the same time in both air- and liquid-cooled versions, so it is possible that many owners of the LCS machines may not even be aware they own one.

P.A. Semi's G5 derivative

When P.A. Semi announced the preliminary pre-production plan of PWRficient processor, there had been persistent rumors that Apple would prepare for its use in its professional line of personal computers.

In 2006, The Register reported that P.A. Semi had formed a tight relationship with Apple, which would result in P.A. Semi promptly delivering processor chips for Apple's personal computer notebook line and possibly desktops. Even in 2006, Apple did not have a laptop version of G5 processor. The processor that would run the personal computers was P.A. Semi's preliminarily proposed processor, PWRficient 1682M (PA6T-1682M). The version that would be sampled for pre-production at third quarter of 2006 was a 2 GHz, dual-core CPU with two DDR2 memory controllers, 2 MB of L2 cache, and support for 8 PCI Express lanes. The sampled chip also has lower heat intensity than Intel's Core Duo, which gives off 9–31 W under normal load.

According to The Register article, P.A. Semi executives believed they were all but assured winning Apple's contract, and CEO Dan Dobberpuhl thought Apple's hints of moving to Intel were just a persuading tactic. At the time, the companies were working for PWRficient software.

Despite the advantages of more compatible architecture, Apple moved to the Intel architecture officially for 'performance-per-watt' reasons. However, P.A. Semi would not be able to ship its low-power multicore product in volume until 2007, which, combined with P.A. Semi's status as a start-up company, seems to have been the final blow to the development of Power Mac computers. However, it was also speculated that Apple switched to Intel processor because Apple could no longer abide the constant delays in performance ramp up, desired native Windows compatibility, or it was Apple's strategy to shift its business focus away from desktop computing to iPod (and subsequently iOS (Apple)) development.

Recycling of cases

Even though the old parts inside the PowerMac G5s are outdated by today's standards, some members of the OSx86 community have devised ways to recycle these old work horses. By doing simple modifications to the G5's case, these case modders are able to fit standard ATX PC computer motherboards into the all aluminum chassis. Also, some members of the "Hackintosh" community install OS X on one of these "Fake Macs". [1]

External links

• Ars Technica: Inside the PowerPC 970 Part 1 and Part 2, very long and detailed
• Ars Technica: A Brief Look at the PowerPC 970
• Ars Technica Review: Power Mac G5 Dual 2.5 GHz