Modding your iMac G4 into a Modern Computer

iMac G4 from Power PC to Modern Intel Desktop

Dremeljunkie and the iMac G4

I started this blog to share some projects, the most important of which became the conversion of the iMac G4 to something that could be used with a modern day processor.  The PowerPC processor went from being slow to obsolete to essentially unusable, which relegated the most elegant desktop computer I've ever used to little more then a showpiece.  As I progressed, I wrote this blog as an experience journal.  I tried several different approaches (probably around 20) and had some success with 9 different methods, these are detailed in my Summary of iMac Mods post.  But, many of these are clearly inferior and more difficult then others.  Some are even potentially dangerous and I've kept those posts up only for historical purposes.  Several posts are even dead ends that were not viable at all.  As a result, this blog can be quite difficult to navigate for those trying to perform this mod.  To help with this, I am writing this post to point those looking to do this in the right direction.  I am thrilled to see that many people remain interested in this computer and this mod and I hope this post will help make the information contained in this blog easier to follow.

The iMac G4

The iMac G4 has one feature that makes it extremely difficult to mod, the neck.  As this is the feature that gives it its defining characteristic, it can not be eliminated or bypassed.  The neck is difficult to open and barely has enough room for the remarkably thin wires that Apple has already passed through it.  The G4 was designed as an all-in-one in two compartments and works unlike any other computer before or since.  Some components usually found outside the LCD are actually inside of it and certain components usually found paired with LCD screens are pulled out and found in the base (the power supply or Motherboard itself).  This made getting a video signal from a different CPU and motherboard through the neck and to the existing monitor difficult.

My goal was always to find a reproducible way to make the screen compatible with a standard video input signal which terminates in the base.  Though, an all-in-one was not overly important to me (I currently use it daily as an external monitor with a Mac Mini) I did go on pair it with several small form factor boards as an all-in-one, the best of which was a Intel NUC.

Next are the hyperlinks to the posts that I believe represent the best ways to do this mod for the different models and sizes.

The Mod

A) The Mods Over The Years:

Summary of iMac Mods:

A Summary and the PROS/CONS of all the G4 mods that I have performed over the years. Although most of these I no longer would recommend, they may still prove valuable to someone and the above hyperlink is where you will find them.

These range from an all-in-one with Intel NUC in the base to a black paintjob on the base and an alternate black monitor attached to the neck to incorporation of parts from an Apple Cinema Display.

B) The 15" iMac G4

The Pinout for the 15" iMac

The most important information needed to perform this mod is the pinout of LCD wires originating from the neck.  Because the iMac G4 uses TMDS signaling it contains the basic components needed to carry a DVI or HDMI signal to the LCD.  This uses the native wires and thus opening the neck is not necessary.

Personally, I found the 15" screen to be uncomfortably small and have never modded one.  The pinout available in this post was provided by modder pgee70.  Thus, only the pinout is seen in this post, but the principals are no different from the 17" mod, only the order and color of the wires vary. Use the 17" mod tutorial as a guide, but follow the pinout seen here instead.

C) The 17" iMac G4

The 17" iMac G4 is easier to mod then the 20" because you do not have to deal with the complexity of the inverters 24V power requirements.  The tutorials provided for the 17" are the most detailed and include video guides.  The principle behind all these mods are very similar and I think the 17" Tutorial is a worthwhile review for anyone attempting any iMac G4 Mod.  As I was focused on making a 20" for myself, the 17" mod is taken to the the level of getting a DVI cable into the base. If you wish to incorporate an Intel NUC in the base, please see the 20" guide as placing an NUC in the base is essentially the same no matter what the size of the screen.

The 17" had processors of 3 different speeds.  What took me a while to figure out was that there are 2 different wire layouts/necks.

The 800mhz varies from the 1 and 1.25Ghz Model.  To figure out which you have please read this post: The Two 17" Necks

The DVI Connector that makes this all possible

iMac G4 17" 800mhz TMDS Pinout

If there is one piece of advise I can give, it would be this: BUY THIS DVI CONNECTOR, the MOLEX PN 74320-4004.  I can not put into words how much easier it makes doing this mod.  It can be found easily and is available from $2-$5 for several of them.  For more details click this hyperlink to my post about it: The Easiest Method.

HERE IS THE HYPERLINK TO THE TUTORIAL ITSELF INCLUDED IN THIS POST ARE EMBEDDED LINKS TO THE VIDEO TUTORIALS.  THIS INCLUDES THE 17" STEP BY STEP GUIDES FOR BOTH 17" NECKS: iMAC G4 17" TMDS to DVI GUIDE

Look Here for the Video Tutorial Only

As this tutorial does not really "use" the base, but only uses the LCD and the neck, the power source I used comes from an AC to molex adapter (12VDC, 5VDC).  There is really no reason not to use the existing iMac power supply as it provides 12V and with a downconverter or (if making an all-in-one) a USB port of your new computer motherboard/NUC, its easy to get a 5V line. The 5V line in the native iMac comes from downconversion on the motherboard itself and is needed to turn on the LCD. For information on using the native power supply use this hyperlink: iMac G4 17" Power Supply.

D) The 20"iMac G4

iMac G4/iMac G5 External Monitors with Mac Mini

This is far and away the machine I have spent the most time modding and would recommend (due to the largest sized monitor).  I currently have two setups that I use using two slightly different methods, both of which work quite well.  The first is an an external monitor with a iMac G5 modded with an Apple Cinema Display with working iSight Camera and mic (click the hyperlink for information on the iMac G5 mod if you're interested).  This mod like the G5 relies on components from a 20" Apple Cinema Display and contains the cinema display powerbrick and a DVD drive (functions as an external drive) in the base of the iMac G4.

The second is an All-In-One Hackintosh 10.9 using only the existing iMac parts itself.  This is by far the easier of the two and leaves the entire base available to place a small motherboard/NUC.  This is also the basis of my tutorial.

To better understand these mods, a little backstory.  The difficulty of the mod was figuring out the inverter which required 24V in order to work.  There is only one neck and the LCD pinout is essentially identical to that of the 1/1.25GHz 17" iMac G4, but I could not get the inverter working, nor could I replace it as it is paper thin and no other inverter would fit in the LCD housing (not even the inverter on the Apple Cinema Display.  The 20" Apple Cinema Display, The iMac G5, and the iMac G4 use essentially the same TMDS panel (The iMac G4 is made by ID Tech, The others by LG) and are pretty much interchangeable (Though some slight physical modifications to the housing sometimes have to be made for it to fit perfectly).  While putting the Apple Cinema Display in the iMac G5 housing, I realized the extent of this compatibility and came up with the idea for the first version of the iMac G4 20" Mod.

1) The iMac G4 20"/Apple Cinema Display Mod

Initially, I had this mod setup as an all-in-one, but then converted to an external monitor with an "external" DVD drive in the base.  I did this because I prefer the mac mini to a hackintosh, but its a personal preference.  This mod uses the iMac G4 housing, inverter, and neck, the LCD screen from either the G4 or the ACD, and the controller board, power supply from the ACD.  Because there are more wires needed for the ACD, the neck does have to be opened and one wire swapped out for a different wire.  The additional wire I used was the LCD signal wires from a different iMac 17" 1/1.25Ghz neck.  So obviously, this mod requires a lot more "stuff".  It is possible, because the controller board of the ADC works with the iMac G4s inverter.  However, there are 8 wires to the ADC inverter and only 7 to the iMac G4 inverter.  Luckily, there is a space for an 8th wire on the G4s inverter and it seems to serve the same function.  Thus, an extra inverter wire is needed (using one of the extra wires in the neck) for it to function properly.  Here are the hyperlinks to the relevant posts.  Again, remember, it was written as a journal and I unfortunately do not have a full step by step tutorial, but can give additional information to anyone who requests it.

The hyperlinks/relevant posts:

The 20" LCD Pinout Alone

The iMac G4 20" Inverter with the Apple Cinema Display Controller

Modding the neck for the Apple Cinema Display Controller

Setting up the base as an All-In-One

Setting up the base as a DVD drive and External Monitor

A Video of this Mod Completed with an ECX board in the base

This is obviously a more complicated and potentially expensive mod then using only the iMac G4 20".  There are some advantages, however, to doing it this way.  As you are using the Apple Cinema Displays controller, it is really an Apple Cinema Display and is recognized as such.  With a controller board, you can adjust the image including resolution, brightness, etc.  You can not do this when hooking directly into the LCD without a controller.  It is also potentially more stable.  The controller board also has 2 USBs and 2 FireWire ports which can be utilized and since the controller is extended to the base of the iMac G4, it is easy to do so.

2) The iMac G4 20" All-In-One-Mod

Although there are some advantages with the first mod, they aren't big enough that I would recommend doing that mod over this one.  This one is much easier and uses only the components of an iMac G4 20" itself, making it much less expensive and wasteful as well.

This uses the same LCD pinout and the native inverter, but uses either a 24V upconverter or the native power supply (recommended) in order to supply the necessary voltage to the inverter.  In the Step by Step I give instructions on either using the native power supply or upconversion method.

Initially, I used a KEEX-6100 ECX board as the motherboard, but then upgraded to the much better Intel NUC Ivy Bridge motherboard, which is vastly superior, as the KEEX was not really intended to be a consumer motherboard.

Hyperlinks/Relevant Posts:

MOST IMPORTANT: THE iMAC 20" STEP BY STEP TUTORIAL (uses the KEEX-6100)

More Information on using the Native 20" iMac G4 Power Supply and how it works

All-In-One Using the Intel NUC in the base

Video of 20" iMac G4 with Intel NUC in base

There are other interesting posts about other smallform factors as well as some info about hackintoshes in general. These posts can all be found within this blog. But, these are the most relevant to those who wish to perform this mod itself.

E) Other Information

The question I most often get is if a new version mac mini will fit and the answer is - no.  The posts block it, so the options are currently, an all-in-one hackintosh or an external monitor.  Personally, as the mac mini does not take up much desk space, and that I do not find hackintoshes to be overly reliable, I would recommend this approach.  Hopefully, apple will one day, reduce the mac mini's footprint, but to date this has not occurred.

The Harmon Kardon Globe Speakers are classic and to some (myself included), important parts of the iMac G4's appearance.  For information on using these speakers and the ridiculous lengths Apple went to to make these speakers as incompatible as possible.  See this post: The Apple Pro Speakers.

For some general advise about modding the iMac G4, this is probably worth a read: iMac G4 Mod Advise.

I hope this helps simplify this site for those attempting to mod their iMac G4s.  It is truly a beautiful machine.  I am holding off on further mods until more then incremental gains are seen.  Redoing the computer for Ivy Bridge to Haswell for instance is not really worth it.  A smaller form factor mac mini is really what I am waiting for.  Thank you for reading and good luck.