Power Macintosh G3 Desktop

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.