How do you replace or upgrade the hard drive in the iMac G3 models? Do these models support "big drives"?

The Apple Support site provides instructions for installing memory in the tray-loading and slot-loading iMac G3 models.

However, Apple does not consider the EIDE (ATA-3) hard drive in the tray-loading models (those with 233 MHz, 266 MHz, and 333 MHz processors) or the Ultra ATA hard drive in all other models (those with 350 MHz and faster processors) to be a "customer-installable part" and declines to provide replacement instructions. Consequently, EveryMac.com does not recommend that users attempt to upgrade the hard drive themselves.

It is quite a bit of work to upgrade or replace the hard drive in the iMac G3 models. Those with limited experience upgrading computers would be wise to instead purchase an external USB or Firewire hard drive for a quick and easy upgrade (models with 400 MHz and faster processors have two Firewire "400" ports). Even those with experience upgrading systems might prefer to purchase an external drive rather than go to the trouble of disassembling the computer and the risk of dealing with an exposed CRT-display.

Nevertheless, those who are ambitious and enjoy tinkering can be thankful to helpful individuals who have written their own step-by-step guides for the tray-loading (now offline) and slot-loading iMac G3 models that cover the hard drive as well as other internal upgrades. If they are still online, you also may be able to refer to the not for public distribution Apple Service Source documents for the tray-loading (PDF) and slot-loading (PDF) iMac G3 models, respectively.

Officially, Apple says that Macs running MacOS X 10.2 or higher released after June 2002 can use "big drives" -- those larger than 128 GB -- which would exclude all iMac G3 models. However, modern external USB and Firewire drive enclosures do make it possible to easily use drives larger than 128 GB. As all iMac G3 models use USB 1.1 -- which is quite slow -- Firewire is recommended for models that have Firewire ports.

For larger internal drives, a third-party driver -- such as one from Intech -- is required. Also note that Don MacDougall of Djonmac (now offline) pointed out:

For all tray loading iMacs, 233 MHz, 266 MHz & 333 MHz. All operating systems must be contained within the first 8 GB of a new hard drive. This means all new hard drives larger than 8 GB must be partitioned. There can be a maximum of 8 partitions.

Ultimately, most users would benefit from a quick and easy external hard drive upgrade. Not only is it easy to use with the iMac G3 but if you buy a model with both Firewire and USB 2.0 ports, it will be easy to use it with other Macs as well.

Site sponsor Other World Computing sells internal hard drives for the tray-loading and slot-loading iMac G3 models as well as quick-and-easy external USB and Firewire hard drives that will work with the iMac G3 series as well as other Macs.