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G4PC: Make A PC Out Of A G4 Case
Author: Drew Lanclos
Date Posted: August 8th, 2001


You walk along the aisles at the LAN party you're attending and see everyone's heavily-modded cases. Quite a few people these days take to drilling holes in their cases to attach handlebars for easy transportation. CaseAce even makes a support system to attach a canvas griphandle so that you can carry all your gear around. Some people are even trying out gaming on a laptop so as to achieve good portability.

The laptop idea offers excellent portability, but at the sacrifice of computing power. Alternatively, you could install handles in your case, but I'm of the opinion that they ruin the aesthetics of the chassis. You can paint and mod your case all day long, but a couple of industrial-strength bars sticking out of it won't make it any prettier.

Then, after having read a few issues of MacAddict about making Windows to be Mac-friendly, the idea dawned on me. More and more Mac hardware these days is PC compatible...Macs even use PCI cards and ATA drives these days. A little bit of investigation into the matter proved to be more promising...

The Macintosh G4 chassis is, more or less, of microATX formfactor, and can accommodate a standard ATX power supply. It has a drop-down tray which houses the motherboard and add-on cards, and it can be easily accessed by pulling on the side-handle, making the system a dream to work on. The side-handle can also be fixed with a lockable lever, preventing anyone from opening the system and screwing around. Last, but most definitely not least, the system has a set of really strong handles that are not only functional, but very stylish as well.

The Chassis

We begin with a look into and around the chassis. Unfortunately, the chassis didn't come with the drive bezels, so I had to obtain those separately.

The victim...

"I have no floppy drive." "Aaaghh!"

Open sesame!

This shows the chassis in its full glory

This plastic mat is part of the door-locking mechanism

The G4 chassis from the rear-view. This walkthrough was brought to you by Mt. Dew Code Red

The G4 chassis has a built-in cooling fan for the PCI cards

"Notice the neatly-tucked cables

In these pictures you can see some of the excellent features and forethought that Apple put into the manufacturing of this case. While it may be manufactured for another type of motherboard, the features will still be useful when we have our brand new motherboard in here.

The Motherboard

One of the first things you'll notice about the G4 chassis is that it only has four slot panels in the back. Unfortunately, this means that we can't use a regular ATX motherboard. Not only would the board be too long, but also three of the slots would be inaccessible. With this in mind, we had to pick a motherboard that would be able to fit in the chassis.

The AOpen MX3L

The motherboard view - Socket 370, 440LX, AGP and three PCI

Yes, it's a rather outdated motherboard, but it came cheaply and I didn't have to buy a new processor or memory for the system. The motherboard will be accompanied by a Celeron 466MHz and a Mushkin PC133 Enhanced 128MB v2.

One of the peculiar things about this motherboard is the location of the floppy cable connector - of all places for it to be, it's on the side of the processor socket! Well, since I've got a bootable CD-ROM drive, I won't really need the floppy anyway. Still, I'll be using one, so it's something I'll need to negotiate with.

The G4 I/O shield

Here's where we can find one of the major complications of this project. The G4 I/O shield is significantly different from the standard ATX I/O shields. Of even more concern is that they're not the same size, which means that I'll need to figure out how to make them compatible.

Backside view

My original plan was to cut a rectangular-sized hole in the G4 shield, and then attach the ATX shield to it. In order to do this, however, I had to break off a tab from the G4 shield which was preventing the motherboard from seating flat. Sorry about the blurry picture, but you should be able to see the place where the tab was broken off.

Sizing up the situation

In order to take sizings on the I/O shield, I needed to know exactly where the motherboard is going to sit. To do this, I put in the video card and an ISA card, and attached them to the PCI slot panels. Since this is the most important thing to line up in the chassis, we can use this as the origin to measure out modifications elsewhere in the chassis.

Something else that the careful eye will notice about the ATX ports on the motherboard is that they don't line up exactly with the opening in the G4. However, the most inconvenience this will cause is the inability to use older joysticks and the microphone jack for the onboard sound. Since I was planning to use a separate sound card anyway, this is really trivial. To make the joystick port fit, I had to use a hex-driver to remove the right-hand screw-bolt. This puts us back on track.

Our "modified" Sharpie

The standoffs in the G4 case weren't anywhere close to where they needed to be for the ATX motherboard, so we needed to put in holes for the new mounts. Without a good pencil or anything, we took apart this Sharpie marker, pulled out the inking tip, shaved it down some, and put it back in where it could reach through the mounting holes to mark on the motherboard tray.

Marking the holes

Here's a shot of myself actually marking the holes. If you look up in the upper right-hand corner, you can also see the EMF trap that normally goes on the back of the G4 shield. Apple puts this stuff all over the seams and linings of the case to help keep EMF from getting out of the case, as well as outside EMF from getting in. I've only seen one other chassis that had this stuff installed, so it's another option that Apple went with to make the Macintosh chassis even sweeter.

Exploring Further

Removing the Torx screws

Next, in order to detach the motherboard tray to make the new screwmounts, we had to take off the plastic side panel. The side panel is only held in by four screws, and then a snap-lock on the inside, shown below. Unfortunately, the motherboard tray itself is riveted into the hinge that attaches it to the bottom of the case.

Undoing the snap-lock on the side panel

The hidden surface of the side panel

Now we're getting into the construction work and such. First, we needed to prepare a good working area. Drilling isn't so terribly messy or hazardous, but using the Dremel will certainly be so. The workbench we're using here has a built-in clamp on the front and right-sides, providing some support for press drillings.

A good project starts with a clean work area

Here, we're using a broken punch to put starter marks in the chassis for drilling pilot holes. The punch creates a small dent in the panel that makes it easier for you to keep the drill steady when you're cutting the panel into swiss cheese. This means that we can't work on the motherboard tray without dragging the rest of the chassis along for the ride.

Under Construction

The punch tool

You know the drill

Here we start putting the holes in the case. Yeah, this shot is a bit sloppy, but it works. We didn't have much scrap wood around, so we didn't really have a good way to support the motherboard tray. I would highly recommend getting a piece of particleboard that's bigger than the tray. Due to the pressures and forces you'll be putting on some parts of the chassis, you're definitely going to need something to support the metal so that it doesn't bend or warp.

Tapping the screwholes

Without a good way to secure the motherboard while we're tapping the screwholes, we ended up just closing the chassis back up and tapping them from the outside. This certainly wasn't the preferred way, but without a good way to support the tray while we're tapping holes, this was really the best way to do it.

Removing the original standoffs

The original G4 motherboard mounts were taller than the motherboard mounts in places, and plus, they're grounded to the chassis. If they were to come in contact with any of the solder points on the motherboard, it could be Bad News(TM). We needed to go ahead and get rid of them. It was quite messy when all was said and done.

Before the cleanup

The Dremel cutting left a lot of metal dust and particles around the chassis. We used a few rags to protect the inside of the chassis while we cut off the tops of the standoffs.

The locking sheet

Since we inserted the new motherboard standoffs into the mounting tray, the plastic sheet needed a few new holes. We went ahead and took the detached plastic sheet into the garage for a couple more holes. Unfortunately, I failed to recognize the "mobile" nature of this plastic sheet. More on this later.

The new holes

This picture shows more clearly the two extra holes I drilled into the sheet to make clearance for the motherboard standoffs. They're showed to the far left and the far right.

The Power Supply

The next obstacle to overcome was the ATX power supply. Thankfully, the PSU fit just fine into the opening, but the AC outlet opening didn't *exactly* line up with the opening on the chassis. This wasn't too terribly important, of course, since the cable would still go in. One could debate extending the hole in the PSU's metal cage so that the outlet would move into the proper position, but the idea of desoldering the socket, cutting open the power supply, and resoldering the outlet, didn't exactly appeal to me, especially since the issue was relatively trivial. The fan grille was also blocking the PSU from moving any further, and I wasn't going to be able to make a satisfactory modification to that.

The PSU opening

It should definitely be noted that if you should wish to pursue this project yourself, there are several different models of the G4 chassis that have been used over the years, one of the major differences being that some have a differently-shaped opening for the power supply. If you try to get one of these cases yourself, make sure that it's either the right one, or that you can return it if it's not.

The I/O Shield

A poor quality shot showing the G4 panel side-by-side with the ATX panel

The G4 shield didn't quite turn out the way I had hoped at first. After evaluating several different tracks to take, I decided that the best method would probably be to cut out the I/O ports from the G4 shield. This would leave some gaps and holes in places, but these could be covered up with some new vinyl sheets that would mask this out, for the most part. Still, it seemed kinda ugly.

The front of the panel

The back of the panel

After tapping, cutting, and slicing, the results weren't especially pretty.

I would've cleaned this up a bit with a rotary file, but I had to cut this part of the project short, due to preparations for would-be Hurricane Barry. I decided to put this step aside and possibly pursue it in the future.

Getting the System Ready

Getting the motherboard set up

Now, I can go ahead and mount the motherboard and start getting set up. I went ahead and installed the motherboard, CPU, memory, and one of the PCI cards. I started to close the chassis just to make sure that everything was cool, and that's when I noticed a small problem. Two separate points on the motherboard were hitting inside the chassis, preventing it from opening.

Those memory slots are going to be a problem

The 2nd and 3rd memory slots stood a bit too tall, and were hitting the CD-ROM bay. Also, a capacitor adjacent to the memory slots had the same problem. The solution? More modifications! My plan was to remove the capacitor from the motherboard and remount it in an out-of-the-way location, using some wires as extension leads.

Unfortunately, I had kids afoot while I was working on this part. Thankfully, they didn't make my crappy soldering job any worse, but what DID happen was still a setback. I took off the wrong capacitor! I ended up having to remount it, and then desolder and reconnect the new capacitor. I also took some time with an X-Acto knife to shave off the tops of the memory slots. You could say that it's a bad thing since now I can't add any more memory, but that memory would've been blocked too, so it's no matter. The photos I had of this were rather poor, so I've left them out. I do have a picture showing the modifications done, though.

The relocated capacitor and the shaved memory slots

Now that this problem was out of the way, I naturally had a new problem to deal with. After testing the case closure, I found I couldn't open it again! All the effort I put into setting up this equipment, and now I couldn't even get to it! After a bit of fiddling, I finally managed to get the case back open, and I discovered the problem.

Minor Setbacks

Oh crap!

The plastic sheet slides whenever the handle is manipulated, and while the motherboard standoffs were out of the way when the handle was shut, they were also keeping the sheet from sliding whenever I tried to manipulate the handle! Oh well…I had to go ahead and cut some more holes in the sheet. Now it slides just fine.

Our little friend, the Delta

I made another silly mistake here. I didn't have any other CPU fans besides my Delta, and so I had to use this one anyway. I know you're not supposed to run these from the motherboard, but I was also fresh out of 3-pin to 4-pin adapters, so I really didn't have a choice. Besides, it wouldn't be operating like this long-term...

The hard disk mount

Unlike most other cases, the G4 chassis doesn't have a hanging drive cage for the hard disk. Instead, due to the location of the motherboard, the hard disks are instead mounted to drive plates on the bottom of the chassis. The picture above shows an IBM 75GXP in the drive tray on the left. There are a total of three mount points on the bottom of the chassis to attach drive trays.

Inserting the drive carriage

The G4 chassis also has a removable drive assembly. To mount CD-ROM and floppy drives in the G4 chassis, you must first pull out the drive assembly, and then insert the drives and screw them down. According to what I've been reading, the G4 is supposed to be able to use any standard ATAPI DVD drives, so I was rather surprised when the CD-ROM I tried to mount in this tray wouldn't quite line up. Instead of putting screws in the side of the assembly like most PC cases, the CD-ROM instead secures from holes in the bottom of the assembly. Unfortunately, the built-in screwholes were a bit too far off. Time to do more drilling.

Still Getting It Ready

My little hacked power switch

The G4 chassis uses a single 20-pin cable to drive the power and reset switches, as well as the LEDs. I haven't managed to figure out the LED system yet, and I don't want to blow them out by supplying too much voltage to them. Still, I did find some schematics showing the positions of the switch pins. I went ahead and used an SPDIF cable to manually trigger the power switch by cutting off the lead ends of the wires and inserting them into pins 5 and 6 of the 20-pin cable. Success! The motherboard boots! This, of course, is a poor long-term solution. I needed some more parts, so I went to my local electronics store. The end result of a few hours of soldering...

The new and improved little hacked power switch

I bought a couple of 20-pin IDC headers and soldered them to a small board with wires linking the relative pins together. With this and a few 2-pin SPDIF cables in tow, I just hooked up the wires to the switch headers. A bit messy, but it's a flexible solution, in the likely case I change motherboards. This particular AOpen board doesn't use normal-sized LED headers, so I'd have to hack something special for those. The IDE light is a four-pin connector, and the power LED is three pins. As an added plus, the 20-pin G4 cable seems to use logic controls to run the 2-color power button LED.

I used another SPDIF cable to bridge the internal fan connection to a motherboard power header, and hacked another cable to link the routed CD-audio cable to the sound card. There's another connection coming out of the front panel that I don't really know anything about. It looks like a 3-pin power cable for a fan, but there's no fan in the place where this supply goes. If anyone out there can give me more information about this, I'd really appreciate it.

Conclusion and Future Looks

I've been running this system solid for about 24 hours now, after having installed Windows 98 on it. It works great, and the system is *very* portable. Now, if only I had an LCD screen to use with it...

It's alive...It's alive!!!

A Macintosh running Windows 98...there's a first...

There's still a few things that I can/should do to this system...For one thing, the GlobalWin FOP-32 is rather large to be using in such small quarters. A Golden Orb would be much more suitable, if not for the dense groupings of capacitors surrounding the CPU socket. Hopefully, the next motherboard I'll be putting in here (I'm hoping for an NV-22 motherboard myself) won't have this problem.

There's also the issue of the LEDs. Hopefully I can get some more information soon so that this case setup will be even more "authentic". Plus, as you can see, the I/O shield needs more work. So this project isn't over, but it's just beginning.

Now, if you've read this article all the way through and you've got bright ideas swirling in your head about doing this yourself, you're probably wondering where to get the chassis. I got mine through connections, but if you're looking to obtain one for yourself, you might want to check with your nearest Apple Authorized Service Center. Ordering the chassis cost me about $160, and the 3.5" and CD bezels should cost you about $45 total. I don't have the CD bezel right now because I haven't ordered it yet, but there are two separate bezels for the CD-ROM drive. One is just a rectangular rim that goes around the CD-ROM faceplate, and the other is the pop-out door you've probably seen in most G3 and G4 towers. If you've got a buddy at an Apple store or service center, then they can probably order both for you.

I'd like to take a moment right now to give thanks to Timothy Seufert's Blue and White G3 to ATX Case Conversion. It has plenty of information about a case in which a Mac user went the other way - Moving his PowerMac G3 into a PC chassis. His info has proven to be nothing short of indispensable in trying to work out the switch and LED configuration.

And lastly, I'd like to thank my wonderful friend, Ken Lee. This was my first case-mod, and while it was a difficult one, he helped me out every step of the way. I couldn't have done it without you, bud. :-)

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