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Some time ago I wrote an article on the Power Macintosh G3 minitower. In This article we are going to take a look at the desktop version of the same G3 and also look at a few minor upgrades I have performed.

Here is my rather yellowed but otherwise in good shape G3 desktop also known as an “Outrigger” case.  The G3 desktop was apples last traditional desktop Macintosh and more or less uses the exact same case as the 7500 and 7600 series I’ve covered in the past. Same speaker on the left and same available drive bays. Mine came with a 1.44mb floppy drive in the obvious floppy drive spot as well as a 24x speed CD-ROM drive below that and a 100mb ZIP drive which were not to uncommon on these machines. The floppy drives on these machines though are powered via a propietary floppy cable and do not have a molex connector on them. I’m unsure if you can use a regular floppy drive.

Here we see the back of the case which is similar but a little different then the 7500 or 7600 due to a different motherboard. There are three slots for expansion cards located on the far right.

We have a power connector and a pass through for a monitor top center and starting at the bottom left we have a SCSI connector followed by a lone ADB port followed by a Ethernet jack and then modem and printer jacks. Lastly we have a display jack for the built in graphics. To the right of the display jack we have another modem jack that my model came with as well as jacks for the audio, a audio out and mic input. This section may vary since it can be swapped out with various “personality cards” which I’ll talk about when we get to the motherboard portion.

Taking the top of the case off reveals pretty much the exact same thing we saw with the 7500/7600 machines.

Opening up the plastic folds and lifting the drive bay compartments reveals the motherboard as well as a space for a hard drive which is mounted on a sled much like in the drive bays. Mine came with the original 4GB hard drive and OS 8.6. The motherboard is much smaller then the motherboard of the 7500 or 7600 in the same case.

Here we have the drive and its sled removed.

The motherboard in the desktop model uses the exact same board as was found in the minitower.

Here is a closer shot of the area on the board were going to look at first with the CPU, RAM and ROM.

1 ) CPU – The G3 macs including the desktop models all used the PowerPC G3 750 CPU. The Desktop model came most commonly with a 233 or 266mhz CPU with 512k6 of L2 backside cache. They also came with a 300mhz CPU with 1mb of L2 cache option. My model was originally a 266mhz version but I upgraded mine to a 300mhz CPU with the 1mb of L2 cache.

The CPU modules have the L2 cache on them and install pretty much like you would on a PC  with a ZIF socket. You simply remove the heatsink, lift the lever and remove and replace your CPU. Keep in mind to change the CPU speed you will need to set jumpers on these motherboards which I will detail further down the page. When I replaced my 266mhz CPU with a 300mhz version it was still running at 266mhz until I set the jumpers although it was detecting the full 1mb of L2 cache as opposed to the 512kb on the original CPU.

2 ) RAM – the G3 has 3 RAM slots for PC66 SDRAM. Generally the machine sold with 32 to 64mb of RAM but is expandable up to 768MB. I have mine with the full 768mb of RAM. You can use faster PC100 or 133 RAM but it will operate as PC66.

Also keep in mind your going to want lower profile RAM since if the RAM is even a little taller then the stock CPU heatsink its going to cause issues with the top fitting. you can make it work but its awkward and pressed down on the motherboard.

Also of note for games. If you are experiencing audio stutter in games as in the example below TURN OFF virtual memory in the OS.


3 ) ROM – Like a lot of earlier Macs the G3 has its ROM on a module. early A revisions of this ROM did not allow slave devices on the IDE bus thus limiting you to one device per IDE controller. This was fixed with revision B and C. I have a later B revision of the ROM, the $77D.45F1 but if you do have an early revision A it is advisable to track down a B or C revision and swap them out. You can find this information under the Apple system Profiler in the OS.

3b ) Video – The onboard video as well as the SGRAM is located under the modem on my machine and next to the PERCH card slot. Early models had the ATI Rage II+ chip on board and later motherboards like mine have the Rage Pro or Rage Pro Turbo chips. This came with 2mb of SGRAM on the board expandable to 6mb.

4 ) “Personality” card or PERCH card – This card basically is the audio card for the Mac providing a simple audio out and mic input. These cards were known as “personality” cards or PERCH cards and are upgradable. My G3 has the simple audio card known as “Whisper” but can be upgraded to the “Wings” card which includes A/V input for video capture. There is also a very rare “Bordeaux” card which features DVD decoding capabilities.

My machine also has the optional 56k model seen just below the PERCH card.

5) Pram Battery which is you CMOS battery for retaining data.

6) CPU and FSB jumpers – This is the jumper block for setting your front side bus, CPU multiplier and PCI clock speed. The G3 comes from the factory with a preinstalled jumper block set to whatever your machines factory configuration is. as seen below.

This is usually under a warranty void type sticker. If your planning to upgrade your CPU or overclock your going to need to set these jumpers. Keep in mind the G3 motherboard uses the smaller 2.00mm sized jumpers but these can usually be found very cheaply on Ebay.

A guide to setting the jumpers can be found here and here.

Here is the jumpers after the factory set block is removed.

7 ) PCI – the G3 has three PCI slots available for expansion with the appropriate MAC version PCI cards.

I have cards installed in two of my three PCI slots. I will detail these upgrades at the end of the article.

8 ) 50 pin SCSI connector for connecting relevant SCSI devices such as hard drives and CD drives.

9) Two ATA-2 IDE connectors for connecting IDE hard drives and CD-Rom drives. If you have an early ROM board then you can only have one device per connection as opposed to two in a slave/master configuration. You are also limited to drives of up to 137gb with the onboard controllers.

10) PSU connector

11) Floppy connector.

My Expansion cards

I have installed two PCI cards in my G3 Macintosh as upgrades

1 ) Sonnet ATA-133 controller card

This is actually the same card I had installed in my G4 MDD Macintosh. I decided to pair this card up with both a 52x speed CDRW drive as well as a 40gb Maxtor ATA-133 hard drive for added speed. This allowed me double my CD speeds and dramatically increase the speed of accessing my hard drive. Using a PCI IDE controller also allows you to overcome the 137gb size barrier of the onboard controller.

2 ) ATI Rage 128 PCI video card w/ DVD decoder.

Not really a huge upgrade over the onboard video but an upgrade that offers a little more power and DVD decoding abilities. The Rage 128 chip is a decent chip that offers good compatibility with games in general and should work fine with late 90’s Mac games. I believe the card pictured above is the 16mb version though there are 32mb cards available. These cards are also fairly cheap and available online. Just be sure to buy the Macintosh versions.

So in the end what do I think of the G3 desktop? I like it. Even though it is basically the same machine as the minitower model I have a soft spot for desktop designs and the desktop just fits into my setup better. The desktop model also seems lighter then the tower model though since it uses the same 7500/7600 series case it comes with the same issues of being made of very brittle plastic. Expect hinges and tabs to bust off when working with this machine. Overall I feel the G3 makes a good rig for playing late 90’s Macintosh games and offers a good range of expansion options. With OS 8 or 9 loaded on your hard drive your good to go.


Growing up I never considered myself a “fanboy”. Even at the height of the 16-bit console wars I never took sides. Sure I preferred the Super Nintendo and considered it the better system but I generally didn’t belittle or shun the Sega Genesis and still wanted and was happy when I received one. This was the general trend with me as far as video game consoles were concerned. I had my favorite that I preferred but I always felt every console had something to offer. Then enter the PC gaming side of me. In my youth I will admit I was an unashamed PC “fanboy”. Ive gone into this before with my previous Macintosh posts as well as said how over time I have grown to accept Macintosh machines and acknowledge they have their place in the great computer scheme of things. I felt I needed to restate this though because of all Macintosh machines no other machine earned my irrational hated and scorn like the iMac G3.

Back in the very late 90’s and early 2000’s I could not comprehend why anyone would want one. To a younger me that couldn’t appreciate the industrial aesthetics as I can now they looked and felt like cheap toys. I felt the playful translucent color schemes were childish and cheap looking. I felt the machine was ridiculously limited in its upgrade options and also overpriced. Why in my own mind would anyone pay a premium for a machine that you could barely upgrade? Of course this is before I came to understand Macintosh as I do now, to appreciate the design and simplicity. You must understand as well that back then as well as now I was primarily a gamer. The computer to me was more a machine for playing games then it was for work, artistic pursuits or perusing the world wide web and as a game machine the iMac generally falls behind when compared to a PC with its massive amount of video card acceleration options as well as bountiful expansion slots and drive bays.

Flash forward some 14 years. I am much more accepting of the Macintosh now and own several, from classic compact versions to late 90’s 7500 machines. One day as part of a computer lot I was picking up I was given a iMac G3 and there it was, my old enemy. Even after all those years I still felt a strange disliking for the thing, “Pointless toy for teenage girls and people that know nothing of computers. Only  fit to surf the web and do homework on, not a “real” computer”. Yet here it is, setup in my apartment where I have very little space. As a matter of fact it is the only Macintosh machine I currently have set up and it has replaced my Mac 7800 as my primary late 90’s Macintosh. Honestly the thing kind of grew on me for the very reasons I once shunned it, simplicity and its interesting design, such irony.

As a gaming machine I still say its is limited compared to its PC contemporaries but really the Mac never was a meant as a ultimate gaming rig and for late 90’s Mac exclusive titles or “Macintosh enhanced” versions of games the iMac G3 is just fine.


There are actually several versions and revisions of the G3 iMac. The greatest version differences though are from the early CD tray loading models and the later slot loading models. I do not own a tray loading model so that may be for a separate review but I do currently own two later slot loading models which differ slightly in design that I will go over now. Both models I own are “indigo” colored models. one being a lesser powered 350mhz version and the other being a more powerful 500mhz version. These machines differ in ways other then CPU speed which I will discuss.

The slot loading models came in CPU speeds ranging from 350 – 700mhz. The machine shown above that I have setup and game on is actually the lesser powered 350mhz model. I chose to use this model for a few reasons. First is for the era of games I’m playing which will be mid to late 90’s a more powerful CPU is really unimportant. After all the machine this replaced was only running a 300mhz G3 at a lower FSB and it performed exactly how I intended. Anything that needs a faster CPU I’ll just use the G4 Mac I acquired.  Second the faster model I own is in considerably worse shape then this model. Its internal speakers are almost dead and its plastic shell is chipped, faded and overall degraded.


So looking at the machines its pretty obvious that this is a “all-in-one” type machine harking back to the original concept of the Macintosh. This is both a blessing and a curse. The up side is the very small footprint this machine takes up on a desktop, at least without anything added such as external speakers and external USB drives. Its extremely simple to setup and only requires a single power cable. The downside of all this is if something fails your pretty much screwed. If the monitor dies on a more traditional setup you just replace the monitor. On this machine if your monitor dies your screwed…well for the most part but I’ll get to that. It also makes the machine very cramped inside and difficult if not impossible in many cases to upgrade.

The monitor is a 1024 x 768 pixel resolution CRT which I’ve found to be adequate in most situations. There is a built in slot loading CD drive bay and that’s about it for built in drives. Most iMacs came with a CD drive but there were models with DVD drives and you can upgrade CD drive versions with DVD drives. Unfortunately I’ve found identifying which model slim DVD drives will work and fit in the iMac to be difficult to figure out over the internet. Below the CD slot we have two headphone audio jacks and to the right a power button. On this model the power button glows a traditional green when powered on but on my 500mhz model the power LED is white.

On the bottom left and right we have two built in speakers. Ive found the built in speakers to be fairly weak and worse yet many of them have degraded considerably over time and have become static filled popping messes. This usually due to the foam around the cones disintegrating over time. Also in my attempts, replacing the speakers seems an almost impossible task. Go ahead, try it if you have one with bad speakers, all I can say is good luck. I found some vague references to latches and having to push down and twist but all my efforts to remove the speakers for replacement proved futile. I was to afraid to snap something as the pressure it seems you need to apply seems excessive. Not even mighty YouTube had a video showing speaker replacement on these things as of the writing of this article. Thankfully this issue can be bypassed by use of external speakers. I would recommend a good pair of external USB speakers to keep the concept of desktop clutter down. There is also a little plastic stand on the bottom of the unit that works as it should. I should also mention the nice carrying handle on the top of the case as well as the fact these machines are fanless so their whisper quiet.

Originally the iMac was sold with a round USB “hockey puck” mouse but these weren’t very well received and a little awkward to use. Later units were sold with the black optical USB Apple Pro mouse like the one I’m using here. These mice were prone to failure due to “flexing and corrosion” so be mindful of that. Later white revisions of the mouse solved these issues. I am using my Pro mouse with a Pro keyboard from around 2000, contemporary with this machine.



This was one of the first computers to finally ditch the floppy drive as standard. Thankfully if you still have a use for floppy drives and disks USB floppy drives were actually made specifically for the iMac and many drives even included color covers that could be swapped out to match your machine. My drive is by VST and you can still find them relatively cheap on eBay boxed. I paid about $12 for mine still sealed.


On the right side of the case we have our various connectors. Two for USB 1.1, two audio jacks for a microphone and speaker as well as a jack for ethernet and a modem as well as a restart button and a “programmers button” that gives access to firmware. On the later 500mhz model you can see two firewire 400 ports were added.


Your likely going to be relying heavily on external USB devices to expand the capabilities of the G3 iMac. Two USB ports doesn’t seem like much in this situation but luckily there are more USB ports on the keyboard as well as the option to use a USB hub device. I keep my keyboard directly plugged into the iMac with my mouse plugged into the keyboard USB port. For any other devices such as my speakers and floppy drive I have a USB hub device plugged into the second jack and those devices running from the hub.



Alright so lets open these things up and see whats inside. To open the iMac you need to flip it over and unscrew the base to get to the motherboard.


CPU – first I’m going to talk about the CPU which I don’t have numbered on the images. To the best of my knowledge it is located on the underside of the motherboard. All of the slot loading  iMacs G3’s run on the PowerPC G3 CPU with a 100mhz front side bus. The models I own are running a 350mhz PPC 750 G3 and a 500mhzmhz PPC 750cx G3. Personally I always liked the power PC line of CPU’s and the G3 is perhaps my favorite. Don’t be fooled by the lower clock speed as these will smoke a 350mhz Pentium II as well as draw less power. More then capable of driving 90’s gaming.

1) Drive tray – This where your slim CD/DVD drive goes as well as the hard drive. The iMac takes an IDE hard drive. Mine was 20GB but I upgraded to an 80GB drive and installed OS 9.2.2 for the best late 90’s game compatibility. I also made a smaller 20GB partition with OS X installed just for fun. I don’t use OS X much on these machines because I do find it runs a tad slow especially on my 350mhz Mac.

2) RAM – The G3 iMac takes PC100 SDRAM and usually came with 64MB or 128MB. This can be upgraded to a max of 1GB via the two 512MB sticks as I have done in the images above.

3) Graphics chip – All versions of the slot loading iMacs use some variation of the Rage 128 chip. My 350mhz iMac sports a Rage 128 Pro with 8mb of RAM while my later 500mhz model has the Rage 128 Ultra chip with 16mb of RAM. Video on the iMac is not upgradable so your pretty much stuck with what you get. That said the Rage chips aren’t bad. They are more then adequate for playing any games from the late 90’s though competent but unimpressive for post 2000’s.

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Now to address the things that are completely lacking on the earlier revision of the slot loading iMac. On opening these machines I was actually surprised how similar yet different these motherboards were. First off if you look at the 500mhz motherboard there are two items circled in blue. The white connector by the RAM slots is a port for a wireless AirPort card. These cards are still compatible with the older revision with an adapter. The second item circled is an actual VGA out port. This is a very welcomed addition as I assume this would allow you to use a separate monitor if you wanted or if the built in monitor died. Personally I think this thing would look very awkward being treated as a tower with a separate monitor but it is a very nice option to have included.

before I conclude I also wanted to show this handy program I have installed.



That’s something you don’t necessarily see every day. I ran across this program at a thrift shop and its pretty nice. This would of been very handy back in the day if all you had was a Macintosh. The program has sound blaster and USB support and it actually makes transferring files across OS’s pretty convenient. For me its mostly a curiosity since I have plenty of Windows 98 machines but its nice to have even if it does just feel wrong.

So what are my final thoughts? I certainly no longer hate the iMac G3 but I still don’t feel they made great gaming computers even in their day. Then again that was never the purpose of these machines. They are beautiful and interesting to look at in an industrial design way and have very little desktop clutter especially without a floppy drive or external speakers but again they are so very limited in expansion options. As a platform for playing 90’s Mac games though It does quite well. It’s kind of a toss up though between this and a beige G3 for 90’s gaming. The beige G3 offers much more expandability in the way of video cards and monitor but internally is an overall slower system with a lower FSB and comes with more cord clutter. For someone like me that is really only interested in a few 90’s mac exclusives and Mac “enhanced” games the iMac G3, a once dismissed machine has ironically become the computer of choice thanks to its small footprint.



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