Beige Logic board The Beige G3 uses Apple's new "Gossamer" logic board. As a compact and versatile motherboard, the Gossamer board was originally designed to be able to support both the high-end PowerPC 604e and the new PowerPC G3, but when initial testing found that the cheaper G3 outperformed the 604e in many benchmarks, this functionality was removed and Apple's 604e-based systems were discontinued. Gossamer supports both onboard and external SCSI (from the custom
MESH IC),
ADB, 10BASE-T
Ethernet, two
MiniDIN-8 serial ports, and onboard
ATI graphics (originally
II+, later updated to
Pro and then Rage Pro Turbo) with a slot for
VRAM upgrades. An external serial port is included; this is the last Power Macintosh model to include one. Three 32-bit PCI slots and one internal
modem slot are present, as well as three SDRAM slots.
ROM Early G3s with Revision A ROMs do not support slave devices on their
IDE controllers, limiting them to one device per bus (normally one optical drive and one hard disk). Additionally, they came with onboard
ATI Rage II+ video. G3s with Revision B ROMs support slave devices on their IDE controllers, and had the onboard video upgraded to ATI Rage Pro. G3s with Revision C ROMs also support slave devices on their IDE controllers, but the most significant technical differences are the newer
Open Firmware version than the previous two models (2.4 vs 2.0f1) and another onboard video upgrade, this time to ATI Rage Pro Turbo. The Beige G3 was the last Power Macintosh with a 4 MiB ROM. The trend of increasingly large ROMs ended after the introduction of the
New World ROM in the Blue and White G3.
Personality cards These machines had no audio circuitry on the logic board; instead, a PERCH slot (a dedicated 182-pin microchannel connector; a superset of the PCI spec, but which does not accept PCI cards) was populated with a "personality card" which provided the audio circuitry. Several "personality cards" were available: •
Whisper was the personality card of the regular versions, providing the Screamer sound
ASIC (with 16-bit, 44.1 kHz audio capabilities with simultaneous I/O) and no video facilities. •
Wings or
Audio/Video Input/Output Card was an A/V "personality card" which, in addition to the audio I/O, included
composite and
S-Video capture and output. •
Bordeaux or
DVD-Video and Audio/Video Card differed from the Wings card in that it did not include a DAV slot, used the Burgundy sound
ASIC (which provided improved sound performance), incorporated a higher performance video capture IC, and included additional circuitry (C-Cube MPEG decoder chip) to support the playback of
DVD movies. The All-In-One does not support the Bordeaux card, as it lacks the connectors for the AIO's front panel and
RGB video cables.
Upgradability CPU: The processor module (a
PowerPC 750 plus L2 cache) was overclockable, i.e. 333 MHz and even 366 MHz or 375 MHz with an 83.3 MHz bus (uncommon). Upgrade kits were available from a number of companies, including Newer Technology, PowerLogix and XLR8, offering G3 processors in the US$1,500 – US$1,800 price range. CPU upgrades as high as a 1.0 GHz G4 or 1.1 GHz G3 would eventually become available, although the user would not see much practical difference in performance on chips faster than 733 MHz due to the system bus limitations, which runs at 66.83 MHz unless overclocked. However, G4 chips running over 533 MHz do not allow the system bus to run faster than 66 MHz, so the bus cannot be overclocked if using one of these G4s. (G3s do allow it.)
PCI cards: Gossamer has three full-length (12") PCI slots, making it capable of taking any PCI cards that have Macintosh drivers available for them (for example, some RealTek-based network adapters, a lot of USB, ATA/IDE [or SATA] and FireWire cards). Common PCI card upgrades include
FireWire cards,
USB cards and FireWire/USB combo cards (especially after the release of the first generation iMac, which caused many vendors to start releasing USB peripherals for the Macintosh), 100BASE-TX or 1000BASE-T (
gigabit Ethernet) network adapter, video cards (e.g. ATI Radeon 7000 and 9200), ATA/EIDE,
Serial ATA and Ultra SCSI cards. Television tuner and radio cards are also often chosen to supplement the AV features on a Wings personality card, or to provide A/V input for models with the Whisper personality card. The All-In-One can be modified to use a PCI video card with the internal monitor.
Personality cards: Some users have upgraded the Whisper personality card with a "Wings" Personality card (which is plugged into the same PERCH slot), and some have upgraded the
ROM to a newer version (Revision A boards to Revision B or Revision C boards).
Hard drives: For storage, the G3 is capable of taking any ATAPI/IDE hard disks, provided that the drive's size is within the 28-bit LBA limit. This means ATA hard disks of up to 137
GB (228 blocks of 512 bytes each) are supported. This limitation can be overcome by using an IDE or SATA PCI-compatible card (e.g. Acard or Sonnet) to enable the use of 2 drives over the 137 GB limit.
Removable storage: The ATAPI/IDE CD-ROM drive can also be replaced with a CD-RW, DVD-ROM or DVD-RW drive, although care must be taken while purchasing the upgrade as the Mac is incompatible with some drives and may refuse to boot at all if an incompatible drive is installed. Also, many third-party optical drives cannot be used as boot devices with the G3, though they work correctly for normal use, and burning on many third party CD-RW and DVD-RW drives requires either commercial drivers or is unsupported even though reading and booting from the drive may still work. It is also capable of taking SCSI storage devices, and with the presence of the right PCI cards, SATA, USB and FireWire storage devices.
SCSI: The presence of an onboard SCSI controller (the SCSI controller is codenamed MESH —
Macintosh
Enhanced
SCSI
Hardware) and connectors permits the use of Mac-enabled SCSI scanners and storage devices, though this runs at only 5 MB/s.
Memory: Apple's spec sheets specify a maximum memory limit of , but independent testers have reported being able to use SDRAM chips, for a total of . Incompatibility has been reported with some DIMM modules in certain configurations- for example, newer single-sided PC‑133 RAM modules will not be detected correctly if they will be detected at all and if the machine can boot with them in place, and the desktop and all-in-one units required the use of low-profile RAM due to space constraints. It should be able to take 168-pin SDRAM of any speed, though it will run at PC66 speeds. The onboard video RAM can be upgraded from 2 MiB to 6 MiB with a 4 MiB SGRAM module (which runs at 83 MHz on Rev. A machines, and 100 MHz on Rev. B and C machines).
Blue and White The faster models (not the 300 MHz model) use the new
copper-based PowerPC G3 CPUs made by
IBM, which use about 25% less power of the Motorola versions clock for clock. The line ranged from 300 to 450 MHz. Despite its 100 MHz system bus and PC100 SDRAM, the 300 MHz B&W G3 performed worse than its 300 MHz Beige predecessor, because it has 512 KiB L2 cache, half of the 300 MHz Beige. The "Revision 2" units fixed the hard drive controller problem with an improved (UDMA-33) IDE controller that supported the standard IDE master/slave two-drive arrangement. This controller worked flawlessly with any drive within the 28-bit LBA constraint. Most Rev. 2 units shipped with a hard disk bracket designed for two drives (in fact Rev. 1 can hold up to three drives side-by-side, while Rev. 2 can hold up to four drives in two stacks, each with two drives) and also included a slightly updated version of the Rage 128 graphics card. The easiest way to tell if the unit is a Rev.2 is by looking at the CMD chip located on the logic board. The CMD chip on Rev. 1 logic boards is PCI646U2 and on Rev. 2 logic boards is 646U2-402. Revision 2 350, 400, and 450 MHz units use the same motherboard as the first "Yikes" version of
Power Mac G4 systems at 350 and 400 MHz ("Sawtooth" AGP-based G4s used a different board) and processor cards for these models are interchangeable. Note that if a G3's firmware has been upgraded (a required update for installing Mac OS 9), it won't accept G4 CPUs until patched with a third-party replacement firmware. A Blue and White G3 that has been upgraded to a G4 is able to run
Mac OS X 10.5 Leopard.
Enclosure The blue and white G3's enclosure design was widely praised at the time for being easy to open up and work on. The entire right side of the case is a door that hinges down by pulling a recessed latch at the top. No components need to be removed or unplugged, and the computer can remain running while opened. The
logic board is positioned in the door, providing access to all components. Hard drives are mounted in a bracket affixed with one screw on the floor of the case. There is room for four internal hard drives and an internal fan is positioned at the side of the case to blow cooling air over them. Removable drives are in a more conventional position at the top of the case. == Technical specifications ==