Replacing your hard drive may seem like a difficult task, but it's not really that hard. Below, you will find information on Firmware, backing up your files, partitioning and static prevention. You will need to know this information before you start taking your computer apart.

What Kind Of Hard Drive To Buy

Early model iMacs can use any IDE/ATA Hard Drive. ATA66, ATA100 and ATA133 will all work great. These hard drives come in 2 speeds, 5400rpm and 7200rpm. Both work fine although the 7200rpm drive will give your iMac a little speed boost. Maxtor, Seagate, IBM, Western Digital are all good name brands. The only thing to be careful of is DO NOT buy a "Serial ATA" or "SATA" hard drive. They are for much newer computers and will not work. The maximum capacity hard drive for early model iMacs is 120GB. You can buy these drives at just about any computer store. Many PC's as well as Macs use the same kind of drive. Here is a photo of a typical hard drive.

Check Your Firmware.

Before doing this upgrade you must have the latest Firmware Update installed on your computer. Firmware is programming that is inserted into the ROM (read only memory) on your computer. The ROM is a chip that is permanently wired to the motherboard of your computer and should not be confused with the RAM (random access memory). ROM contains the programming that allows your computer to be booted up each time you turn it on. All early model iMacs (233mhz, 266mhz & 333mhz) need to have iMac Firmware Update v1.2 installed before upgrading the hard drive. If you don't know if your Firmware is updated or not, you can download the updater from Apple (above link) and try to run it. It will tell you if it is needed or not. If it is needed, read the "Read Me" file and follow the instructions carefully.

Backing Up Your Data

If you want to save what is currently on your iMac hard drive, you must back it up before starting this upgrade. If you have a CD or DVD burner you can easily backup the entire contents of your hard drive to CD's or DVD's or better yet, use an external USB hard drive. After the new drive is installed, you can put everything back just the way it was on your old hard drive. However if you don't have a CD/DVD burner or external hard drive you will have to use some other type of data storage. There is Internet backup services that will store your data on a remote computer, but space is limited.

Static Strap

A is used to prevent static electricity from damaging the sensitive components like the Ram in your iMac. It physically connects your body to the chassis of the computer, thereby providing a safe route for the static to travel though. Consequently, if you don't use a static strap and you touch a sensitive component on the computer, the static charge that is built up in your body could travel from your finger to the component and instantly damage it. These straps can be purchased at your local electronics store but if you are a little bit inventive or just plain cheap like me, you can . In order for the Static Strap to work you need to have one end taped to your skin, usually wrist or ankle and the other end needs to be clipped to the frame of the once it is out of the computer.

Tools & Workspace

The only tool you need is a clean Phillips (star) screwdriver. Make sure it is not magnetised. For a workspace, you need a clean, dry, dust free table, a soft cloth or towel to protect the screen of your iMac and a couple of small containers for screws. The are 10 screws to remove. Some look similar to others so it is a good idea to take a good look at each one as you take it out.

Jumper Settings

Before you install the hard drive you must check its jumper settings. Most hard drives come with their jumper settings already set to "Master or Single" which is what you want. However, sometimes they get changed for whatever reason and need to be changed back. Each hard drive manufacturer has different jumper settings. A diagram of the settings for that drive is usually printed right on the top of the hard drive. If it's not there, check the box it came in or go to the manufacturers website and they will have the settings there. To change the settings, just pull out the clip and put it back in the appropriate spot. Here is a diagram of where to find the and what they look like.

Formatting & Partitioning The Hard Drive

Partitioning is simply dividing your hard drive into two or more parts called partitions. Each partition will have its own icon that will sit on your desktop just like your present hard drive does. Partitioning (& formatting) are done after you install your new hard drive but you should have a partition scheme figured out before you start, that way you will be familiar with the concept of partitioning and be ready to enter the information when needed.
Important: For all tray loading iMac's, 233mhz, 266mhz & 333mhz. All operating systems must be contained within the first 8GB of a new hard drive. This means all new hard drives larger than 8GB must be partitioned. There can be a maximum of 8 partitions. Click for examples of different partition schemes. When formatting & partitioning you will lose approximately 4%-5% of the hard drive space. This is unfortunately unavoidable. So for the examples given in the above link, be aware that I have not taken this into account because it makes it easier to explain this way. When you actually perform the procedure, the lost megabytes will be deducted from the last partition.

What To Do With Your Old Drive

Before taking out your old hard drive, you should think about what you are going to do with it. If you are going to throw it away or just leave it laying around, you should completely erase it before taking it out of the iMac. This is especially true if you keep sensitive information on it. You wouldn't want someone to pull it out of the garbage and plug it into another computer and have access to all your files. There are two ways of erasing a hard drive. Click here for a description of both. If you decide to do this, it should be the very last thing you do before starting the hard drive upgrade procedure.