Power Mac G4

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Power Mac G4

The "Graphite" Power Mac G4
Developer	Apple Computer, Inc.
Type	Mini Tower
Release date	August 31, 1999 (19 years ago)
Discontinued	June 20, 2004
CPU	single or dual PowerPC G4, 350 MHz – 1.42 GHz (Up to 2 GHz processors through 3rd-party.)
Predecessor	Power Macintosh G3
Successor	Power Mac G5

The Power Mac G4 is a series of personal computers designed, manufactured, and sold by Apple Computer, Inc. from 1999 to 2004 as part of the Power Macintosh line. Built around the PowerPC G4 series of microprocessors, the Power Mac G4 was marketed by Apple as the first "personal supercomputers",^[1] reaching speeds of 4 to 20 gigaFLOPS; this was the first existing Macintosh product to be officially shortened as "Mac", and is the last Mac able to boot into classic Mac OS.

The enclosure style introduced with the Power Macintosh G3 (Blue and White) was retained through its entire five year production run of the Power Mac G4, albeit with significant changes to match Apple's evolving industrial design and to accommodate increasing cooling needs; the G4 and the enclosure were retired with the introduction of the Power Mac G5.

PCI Graphics/AGP Graphics/Gigabit Ethernet[edit]

"Graphite" Power Mac G4

Rear view of a "Graphite" Power Mac G4, showing the available ports.

The original Power Mac G4 was introduced at the Seybold conference in San Francisco on August 31, 1999.^[2] There were two variants, officially titled Power Mac G4 (AGP Graphics) with 400 MHz, 450 MHz and 500 MHz configurations available, and Power Mac G4 (PCI Graphics), with 350 MHz and 400 MHz configurations. Colloquially, this generation of Power Mac is referred to as "Graphite", owing to the colors of the case being similar to the iMac G3 Graphite.

Apple originally planned to ship the 500 MHz configuration in October 1999, but they were forced to postpone this because of poor yield of the CPUs. In response, Apple reduced the clock speed of the processor in each configuration by 50 MHz (making the options 350 MHz, 400 MHz and 450 MHz), which caused some controversy because they did not lower the original prices.^[3]

The early 400 MHz (later 350 MHz) PCI-based version used a motherboard identical to the one used in Power Macintosh G3 (Blue and White) computers including the use of Zero Insertion Force (ZIF) processors sockets^[4] (minus the ADB port), in a "graphite" colored case and with the new Motorola PowerPC 7400 (G4) CPU. The higher-speed models, code name "Sawtooth", used a greatly modified motherboard design with AGP 2x graphics (replacing the 66 MHz PCI slot).

The PCI variant was discontinued at the end of 1999.^[5]

The machines featured DVD-ROM drives as standard; the 400 MHz and 450 MHz versions had 100 MB Zip drives as standard equipment, and as an option on the 350 MHz Sawtooth. This series had a 100 MHz system bus and four PC100 SDRAM slots for up to 2 GB of RAM (1.5 GB under Mac OS 9). The AGP Power Macs were the first to include an AirPort slot and DVI video port; the computers could house a total of three hard drives, two 128 GB ATA hard drives and up to a single 20GB SCSI hard drive, with the installation of a SCSI card.

The 500 MHz version was reintroduced on February 16, 2000, accompanied by 400 MHz and 450 MHz models. DVD-RAM and Zip drives featured on these later 450 MHz and 500 MHz versions and were an option on the 400 MHz.

The Power Mac G4 (Gigabit Ethernet) model was introduced at Macworld Expo New York on July 19, 2000; the new revision included dual-processor 450 MHz and 500 MHz versions, and a low-end single CPU 400 MHz model. It was also the first personal computer to include gigabit Ethernet as standard. Most people saw this revision as a stopgap release, because higher clocked G4s were not available; the G4’s Motorola XPC107 “Grackle” PCI/Memory controller prevented the G4 from hitting speeds higher than 500 MHz.^{[citation needed]} The dual 500 MHz models featured DVD-RAM optical drive. Zip drives were optional on all models; these models also introduced Apple's proprietary Apple Display Connector video port.

Digital Audio/Quicksilver[edit]

Power Mac G4 (Quicksilver)

A new line with a revamped motherboard but the familiar "Graphite" case debuted on January 9, 2001. Known officially as the Power Mac G4 (Digital Audio), it is in effect a Quicksilver design inside the Graphite enclosure. Motorola had added a seventh pipeline stage in the new PowerPC G4 design to achieve faster clock frequencies. New features included a fourth PCI slot, a 133 MHz system bus, an improved 4X AGP slot, and a new "digital audio" Tripath Class T amplifier sound system; the models were offered in 466 MHz, 533 MHz, dual 533 MHz, 667 MHz and 733 MHz configurations, the latter two using a newer PowerPC 7450 processor. The number of RAM slots was reduced to three, accommodating up to 1.5 Gigabytes of PC133 SDRAM.

The 733 MHz model was the first Macintosh to include a built-in DVD-R or Apple-branded SuperDrive, the rest of the line became the first Macs to ship with CD-RW drives. This was also the first series of Macs to include an Nvidia graphics card, the GeForce 2MX.

At Macworld Expo New York on July 18, 2001, a new line debuted featuring a cosmetically redesigned case known as Quicksilver, and various upgrades to the specifications. It was available in 733 MHz, 867 MHz and dual 800 MHz configurations. The 733 MHz model was notable for not having a level three cache. The SuperDrive was offered on the mid-range 867 MHz model, and UltraATA/100 hard drives were offered on all models. The internal speaker received an upgrade, using a Harman/Kardon speaker.

Quicksilver received criticism in MacWorld's review for removing the "eject" button and the manual eject pinhole, as well as the pass-through monitor power plug, and for the base specification of 128 MB RAM as being insufficient for running Mac OS X.^[6]

Updated Quicksilver machines, officially named Power Mac G4 (QuickSilver 2002), were introduced on January 28, 2002 with 800 MHz, 933 MHz and dual 1 GHz configurations. This was the first Mac to reach 1 GHz. Again, the low end 800 MHz model did not include any level three cache. The graphics in this series were provided by an Nvidia GeForce4 MX400 card; some of these models have ATA controllers with 48 bit LBA for hard drives larger than 128 GB.

Mirrored Drive Doors/FW800[edit]

Power Mac G4 (Mirrored Drive Doors)

Power Mac G4 MDD with open case

Another generation of Apple Power Mac G4s, officially named "Mirrored Drive Doors" (MDD), was introduced on August 13, 2002, featuring both a new Xserve-derived DDR motherboard architecture and a new case design. All models were available in dual processor configurations running at 867 MHz, 1 GHz or 1.25 GHz. As with the Xserves, the PowerPC 7455 CPU used does not have a DDR frontside bus, meaning the CPU could only use at most 50% of the new system's theoretical memory bandwidth, providing no improvement over previous models; the rest was available to the graphics card and I/O systems. A single processor 1.25 GHz model would be the last Power Mac G4 the company offered to the public after the announcement of the new Power Mac G5, introduced in June 2003.

The last real update to the Power Mac G4 line was on January 28, 2003 offering dual 1.42 GHz PowerPC 7455 processors, with features not seen in previous DDR models: built-in FireWire 800 connector, optional integrated Bluetooth, and optional integrated AirPort Extreme. These were also the first Power Macs that could not boot into Mac OS 9.

With the launch of the Power Mac G5 on June 23, 2003, Apple re-introduced the August 2002 Power Mac G4 because of perceived demand for Mac OS 9 machines. Between that, its low price-tag, and the delayed availability of Power Mac G5s, it proved a strong seller for a relatively short time. Production stopped on June 27, 2004 and the remaining inventory was liquidated, ending the 20-year legacy of Classic Mac OS support with its discontinuation.

Noise issues[edit]

A limited range of serial numbers of this model was noted for a noisy fan, earning them the unofficial designation "Windtunnel G4" in some communities. Noise complaints became such a problem that Apple later replaced the machine's power supply (PSU) and primary cooling fan with quieter versions, and initiated a voluntary do-it-yourself (DIY) replacement scheme for all previously sold machines. A very common issue in the MDD models was a failing PSU.

It is believed^[7] that the reason for the problem is a bug in the CPU with handling cache coherency in dual cpu setups when switching the CPU to low power states.^[8] To address this problem, Apple released a firmware update, disabling switching to low power states.

In a low power state, each CPU would have only consumed about 5 Watts^[9] (or even less when switching to even lower power states), making for 10 Watts needing to be cooled, but when run in full power mode (as to circumvent the cache problem), each CPU does consume about 50 Watts making for a total of 100 Watts^[10]—essentially the upper limit for which the cooling system was designed, making the fans run at full speed, even when the machine is mostly idle.

The machine can be configured to use only a single CPU at the Open Firmware prompt.^[11] There was also a developer utility^[12] to switch between single and dual CPU via a System Preferences preference pane.^[13] Using that API, a tool was developed^[14] to switch to single CPU on low load, enabling the low power mode and switching to dual CPU mode only when required. Soon after suggesting that hack to Apple, a new firmware was released,^[15] disabling the API for switching between single and dual CPU modes.^[16]

At least some MDD models also have a design flaw resulting in noise in the audio-out, picking up interference from the mouse, graphics card, hard drive and other hardware. According to Apple, this is a ground loop issue, and only occurs when used with professional balanced signal audio equipment,^[17] however some audio experts contended it is due to shielding defects on the motherboard and affects all equipment.^[18]

Timeline of Power Macintosh models

See also[edit]

Wikimedia Commons has media related to Power Mac G4.

• Power Mac G4 Cube

Notes[edit]