Power Macintosh G3/266 Processor Upgrade Page


The Power Macintosh G3/266 was part of the first generation of machines from Apple based on the new 750 PowerPC or G3 processor and came in two flavors, the desktop and the minitower. For an additional $600 the tower configuration offered better storage capacity with a larger hard drive (6GB vs. 4GB) and an internal Zip drive for hauling those weighty graphics files around. Both machines came with a propriatary "Personality Card" which added functionality to the machine. The personality card in the desktop model provides 16 bit stereo sound in and out as well as a connector for an internal modem. The tower personality card offered these features as well as 24 bit video in and out.

When the G3/266 was first released MacAddict pitted it against an 8600/300, a machine with a 604e processor running at 300MHz. They found the G3/266 completed a suite of Photoshop functions 78% faster than the 8600. NortonUtilities gave the G3 a score roughly 30% higher than the 8600. These scores reflect the advantages of the G3 over the 604e chip. The G3 chip found in the 266Mhz desktop model was a faster version of the PowerPC processor. It's speed was enhanced because the L2 cache resides on a dedicated backside bus running at 133Mhz between processor and cache. Previously L2 cache performance was limited by the speed of the main logic board bus which runs at a much slower speed.

PowerMac G3/266 Facts at a Glance

  • Processor: G3 (750), 266 MHz
  • 512K Backside Cache @ 133 MHz
  • 66 MHz System Bus
  • Drive: 4 or 6GB IDE
  • Internal Zip Drive (Tower)
  • Internal SCSI: Standard SCSI 5MB per sec
  • Slots: 3 PCI 1 Comm
  • Installed RAM: 32MB (384 Max)
  • RAM Slots: 3, 168-pin DIMM
  • Min RAM Speed: 10 ns
  • Installed SGRAM: 2MB (6 Max)
  • Introduced: 11/15/97
  • Initial Retail Price: $2,399, $2,999 (Tower)

The processor and cache reside in on a removable card that fits into a PC type Zif socket making it easy to replace with a faster processor. The main system bus of these G3 machines runs at 66Mhz (previous Macs ran at 50Mhz). The G3/266 comes with 32MB SDRAM, expandable to 768 MB using the 3 DIMM sockets (standard profile 128MB DIMMs will not fit in the desktop machine). The graphics controller is the ATI 3D Rage II+ and the machine come standard with 2MB SGRAM graphics memory which allows for millions of colors (32-bit) at up to 832 x 624 resolution. Graphics memory is expandable to 6MB which will allow millions of colors at higher resolutions and faster 3D performance. There are 3 PCI slots for add on cards and a proprietary slot for the included personality card. The drive is a 4GB EIDE on the Desktop and 6 GB on the Tower, and the CD ROM is 24x. The Tower machine has one free 5.23" drive bay (the other is filled with the internal Zip drive) and both machines have external SCSI connectors (5Mbytes per second). The machine case is easy to get into and the simplicity of the new logic board design make upgrades a snap.

Below you will find the MacBench 4.0 results for most of the processor upgrades available for this machine. These results are what the individual manufactures publish for their cards. In other words the speed trials were run by the manufacturer. For an independent evaluation of these cards check the Processor Upgrade Page to see if we have results available. The bar graphs below express results as a percentage of improvement over the base machine, which receives a score of 100%. Further down the page you will find a table with the actual MacBench score.

MacBench Absolute Scores

Processor Upgrade Card

MacBench 4.0 Processor Score

Power Macintosh G3/266 895
XLR8 MACh Speed G3Z/300/200/1MB 1005
NewerTechnology MAXpower G3ZIF/333/166/1MB 1049
XLR8 MACh Speed G3Z/333/167/1MB 1117
XLR8 MACh Speed G3Z/366/183/1MB 1228
PowerLogix PowerForce G3Z/333/222/1MB 1225
XLR8 MACh Speed G3Z/400/200/1MB 1341
NewerTechnology MAXpower G3ZIF/366/183/1MB 1349
PowerLogix PowerForce G3Z/366/244/1MB 1350
NewerTechnology MAXpower G3ZIF/400/200/1MB 1417
PowerLogix PowerForce G3Z/400/266/1MB 1468
Sonnet Encore G3/366/183/1MB 1350
Sonnet Encore G3/400/200/1MB 1475
PowerLogix PowerForce G3Z/466/233/1MB 1722
Newer Technology MAXpowr 466/233/1MB * 1647


Internal Links

  • More information on the G3/266
  • Processor Card Upgrade Index
  • Graphics Card Upgrades Index
  • Upgrades By Machine
  • Hardware Index
  • Comparison of Processor Chip Speeds
  • Older Machine Benchmark Comparisons
  • Processor Upgrade Cards Manufacturers Links
  • External Links

  • Apple's online specs for the G3/266 Desktop
  • LowEndMac's information page for this machine
  • EveryMac's information page for this machine
  • Apple's online specs for the G3/266 Tower
  • Processor Card Reviews
  • Index of all online Macintosh hardware and software reviews