Power Mac G5

Power Mac G5

Infobox Computer
name = Power Mac G5
developer = Apple Computer, Inc.
type = Desktop
photo =
caption = Apple Power Mac G5
first_release_date = June 24, 2003
discontinuation_date = August 7, 2006
processor = Single or dual PowerPC G5,
1.6 - 2.7 GHz
baseprice = USD$1999 (as of 2006)
The Power Mac G5 is Apple's marketing name for models of the Power Macintosh which contain the PowerPC G5 CPU. The professional-grade computer was the most powerful in Apple's lineup when it was introduced, 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 aluminum chassis. [Power Mac G5 User's Guide, 2005, page 5]


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 MB of RAM, an 80 GB hard drive, and could employ a maximum of 4 GB of RAM. The 1.8 and dual-processor 2.0 GHz models shipped with 512 MB of RAM, and could employ a maximum of 8 GB of RAM. The dual-processor model also included an ATI Radeon 9600 graphics card.

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 includes processors with speeds of up to 3.2 GHz.

Also during the presentation, Apple 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 PowerPC "G5" (actually 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 58 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 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 four gigabyte addressable memory limit of traditional 32-bit processors. Currently, the Power Mac G5 can hold sixteen gigabytes of RAM using eight memory slots with 2 GiB per stick. All modern 32-bit x86 processors since the Pentium Pro have had 36-bit memory address capability. The Power Mac G5's PowerPC 970 processor itself is capable of addressing 242 bytes (4 terabytes) of physical RAM and 264 bytes (8 exbibytes) of Virtual RAM. The memory in this final revision of the Power Mac G5 is Dual-Channel DDR2 PC4200, with support for ECC memory.

Product revision history

(Note: DP designates a dual-processor machine, and SP designates a single-processor machine)
*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 liquid-cooled DP 2.5 GHz replace all previous models
*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), DP 2.0GHz → 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 U.S.
*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), all with DDR2 memory, and PCI Express expansion in place of PCI-X. [cite web|url=http://www.apple.com/pr/library/2005/oct/19pmg5.html |title=Apple Introduces Power Mac G5 Quad & Power Mac G5 Dual |accessdate=2008-06-27 |date=2005-10-19 |publisher=Apple Inc.] [cite web|url=http://www.computerworld.com/softwaretopics/os/macos/story/0,10801,106263,00.html |title=The Power Mac G5 Quad: Seat belt not included |accessdate=2008-06-27 |last=Kossovsky |first=Yuval |date=2005-11-16 |work=Computerworld |publisher=International Data Group] [cite web|url=http://www.macworld.com/article/48071/2005/11/quadreview.html |title=Power Mac G5 Quad: Fast performance at its core |accessdate=2008-06-27 |last=Norr |first=Henry |date=2005-11-22 |work=Macworld |publisher=International Data Group] 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: [http://www.apple.com/support/downloads/powermacg5late2004firmwareupdatev11.html Highly important SMU Update for G5 (Late 2004)] (Apple, 2006)
*27 September 2004: [http://www.apple.com/support/downloads/powermacg5uniprocessor515f2firmwareupdate.html Version 5.1.5f2] (Apple, 2004)
*17 November 2004: [http://www.apple.com/support/downloads/powermacg5june2004firmwareupdate.html Version 5.1.8f7] (Apple, 2004)

Noise problems

Early versions of dual processor G5 computers have noise problems. The first one is ground loop-based interference [cite web|url=http://docs.info.apple.com/article.html?artnum=86655 |title=Macintosh: Solutions for noise in the audio signal |accessdate=2008-06-27 |date=2004-12-16 |publisher=Apple Inc.] , 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. The power draw fluctuation was later attributed to the lack of power management features in the single-core processors.Fact|date=October 2008 Apple eventually posted the chirping bug information on its support site. [cite web|url=http://docs.info.apple.com/article.html?artnum=86523 |title=Power Mac G5: I hear buzzes, beeps, or humming |accessdate=2008-06-27 |date=2005-09-01 |publisher=Apple Inc.]

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, where users would expect the machines to be quiet.

P.A. Semi's G5 derivative

When P.A. Semi announced the production plan of PWRficient processor [cite web|url=http://www.eetimes.com/news/latest/showArticle.jhtml?articleID=172303041 |title=PowerPC play: He shoots ... |accessdate=2008-06-27 |last=Merritt |first=Rick |date=2005-10-24 |work=EE Times |publisher=United Business Media] , there had been rumors that Apple would use it in its computers. [cite web|url=http://www.linleygroup.com/npu/Newsletter/wire051110.html |title=The Linley Group |accessdate=2008-06-27 |last=Gwennap |first=Linley |coauthors=Bob Wheeler, Jag Bolaria, Joseph Byrne |date=2005-11-10 |work=The Linley Wire |publisher=The Linley Group]

In 2006, The Register reported that P.A. Semi formed a tight relationship with Apple, which would result in P.A. Semi delivering chips for Apple's notebook line and possibly desktops. [cite web|url=http://www.theregister.com/2006/05/19/pasemi_apple/ |title=Apple shunned superstar chip start-up for Intel |accessdate=2008-06-27 |last=Vance |first=Ashlee |date=2006-05-19 |work=The Register |publisher=The Register] Even in 2006, Apple did not have a laptop version of G5. The processor that would run the computers was P.A. Semi's first processor, PWRficient 1682M (PA6T-1682M). The version that would be sampled at third quarter of 2006 was a 2GHz, dual-core CPU with two DDR2 memory controllers, 2MB of L2 cache, and support for 8 PCI Express lanes. The sampled chip also has lower power consumption than Intel's Core Duo, which uses 21-25 watts.

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 bargaining tactic. At the time, the companies were working for PWRficient software. Dobberpuhl was furious when he learned of the Intel deal.

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, combining P.A. Semi's status as a start-up company, it may be the final blow needed to end the development of Power Mac computers. However, it was also speculated that Apple switched to Intel processor because Apple no longer cared about making leading-edge computer hardware [cite web|url=http://arstechnica.com/news.ars/post/20051026-5486.html |title=P.A. Semi's major PowerPC announcement, and looking back at The Switch |accessdate=2008-06-27 |last=Stokes |first=Jon |date=2005-10-26 |work=Ars Technica |publisher=Ars Technica] , or it was Apple's strategy to shift its business focus to iPod and its ecosystem.


External links

* [http://arstechnica.com/cpu/02q2/ppc970/ppc970-1.html Ars Technica: Inside the PowerPC 970 Part 1] and [http://arstechnica.com/cpu/03q1/ppc970/ppc970-0.html Part 2] , very long and detailed
* [http://arstechnica.com/wankerdesk/3q02/powerpc.html Ars Technica: A Brief Look at the PowerPC 970]
* [http://arstechnica.com/reviews/004/G5/G5-1.html Ars Technica Review: Power Mac G5 Dual 2.5 GHz] Navbox with columns
name = Navbox with columns/doc
state = uncollapsed
title = Apple Model Navigation
colstyle = text-align:center;background:silver;
colwidth = 25%
col1header = Replaced
col2header = Current Model
col3header = Successor
col1 = Power Mac G4
col2 = Power Mac G5
col3 = Mac Pro
col1footer = Preceding Family Model
col2footer = June 24, 2003
col3footer = Following Family Model

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