G3 Upgrades for the Level 2 Cache Slot

This page covers G3 upgrades that fit in the Level 2 cache socket of the Power Macintosh 4400, 5400, 5500, 6400, 6500, 7220; Performa 54xx, 6360, and 64xx; Twentieth Anniversary Mac; StarMax 3000, 4000; Power Computing PowerBase; Umax SuperMac C500, and C600. Check with the manufacturer of the upgrade to see which models are compatible.

  • Bare Feats studies cache size, cache speed, and motherboard cache

Each accelerator will provide several times the performance of the processors installed in these older Macs. Be sure to read That Extra 10% to help you decide which upgrade provides the best value for you.

IBM, Motorola, and Apple have done a phenomenal job in creating the Power PC 750 CPU (a.k.a. G3) and the computers that use it. An entire industry has sprung up selling G3 cards to owners of second-generation Power Macs with processor cards.

The information is as accurate as I can find, but specifications and availability are subject to change; I suggest you check with the manufacturer to verify current models. Prices keep dropping, so these prices may be outdated. (Prices are in $US.)

In fact, models are added and discontinued so often, it’s impossible to keep track of which models are current.

  • Accelerate Your Mac used to have user reports on various G3 upgrades (alas, never archived), and Macworld did a big comparison article in the July 1998 issue (not available online).

Note that computers upgraded with these cards may not support Mac OS X. (Apple has emphatically stated that OS X will run on all Macs designed with a G3 processor but has never promised any support for G3-upgraded models.)

Further, models with AV cards may require special adapters or versions of the card at additional cost.

Discontinued accelerators are listed for historical reasons.

Manufacturer CPU
5.0 rating*
Street Price
adjustable bus
320 MHz 1 MB 160 MHz disc.
300 MHz 512 KB 150 MHz disc.
260 MHz 512 KB 130 MHz disc.
Newer Tech
400 MHz 1 MB 200 MHz disc.
400 MHz 1 MB 200 MHz disc.
300 MHz 512 KB 150 MHz disc.
Phase 5
300 MHz 1 MB 150 MHz disc.
400 MHz 1 MB 160 MHz disc.
320 MHz 1 MB 160 MHz disc.
240 MHz 512 KB 120 MHz disc.
Sonnet Technologies
Crescendo/L2 G3
updated 5/12/03
500 MHz 1 MB 250 MHz $250
400 MHz 1 MB 200 MHz $200
400 MHz 512 KB 133 MHz disc.
350 MHz 1 MB 175 MHz disc.
300 MHz 512 KB 150 MHz disc.
250 MHz 512 KB 125 MHz disc.
VPower PF
320 MHz 512 KB 120 MHz disc.
240 MHz 1 MB 160 MHz disc.

* Processor score from MacWeek or Macworld when possible, but many MacBench ratings are from manufacturers. End-user results will vary based on a number of factors including bus speed and OS used.

** Estimated value is MacBench rating divided by price. The figure is based on an estimated MacBench score for untested cards. Higher numbers represent more bang for the buck.


This page was created on December 1, 1999 and has been updated occasionally.