Logic board has been pulled from an iMac with a dead CRT. Modem and power converter have been removed. Power is supplied via an ATX power supply connected thru an ATX to iMac converter from SlowMac.
RGB output has been adapted to VGA at 800x600 via a custom wired adaptor. I could have removed the iMacs RGB board and gone directly from the logic board to the VGA, but the harness the iMac had was too short to reach the video port on the case, and I didn't feel like wiring up a longer cable that fit the logic board. I already had the RGB to VGA cable from a previous setup, so I just used it to save some effort.
The CD ROM drive is a Sony CD-RW. It has been connected to the iMac's CD ROM ATAPI connector. A cheap CompUSA 44 pin IDE to 40 pin IDE adaptor was used (laptop to desktop IDE adaptor). Note: Apple did not follow the 44 pin IDE spec when they created the 50 pin CD ROM connector. As a result, the adaptor had to have a pin cut from ground or it would short a +5v to ground on the iMac logic board. I used a scratch awl to scratch thru the ground trace from the offending pin. The remaining pins could be ignored on this adaptor as they didn't cross connect to anything that caused a short (check your adaptor before you plug it in to be sure it is safe). Also, the adaptor has to be inserted so that pins 1-4 are exposed on the logic board (pin 1 of the adaptor lines up with pin 5 on the logic board).
The ATX to iMac power adaptor came with a power button on it, however I connected the case power button to pins 19/20 on the audio header to take advantage of the iMac's power circuit instead. This has the added advantage of allowing me to turn off the iMac via the power button as well (the one on the adaptor only turned it on, it could not also turn it off). This was actually done on the advice of the person who made the ATX power adaptor.
The case's power LED was jumpered to the power LED output on the ATX adaptor.
I did not connect the audio on this setup. Since it will be in a server rack locked in a closet, I didn't feel the need to wire in a speaker
Keyboard and Mouse are connected via a Belkin USB to PS/2 adaptor. The iMac is able to recognize the adaptor and the PS/2 keyboard and mouse without additional drivers. The adaptor was about the same cost as a used USB iMac keyboard and mouse ($30). I have since found the adaptor even cheaper ($15 for the Belkin, $8.00 for a generic brand that claims Mac compatibility).
The ethernet is connected to the back of the case using a pigtail to extend from the logic board to the cutout in the case. I wasn't able to find a glue that would adhere to the metal of the case, so both the ethernet and the PS/2 keyboard and mouse connectors are held in place via a few cable ties. It isn't as pretty as I would have liked, but it gets the job done (and for a server that is unlikely to have the keyboard and mouse removed very often, it will be more than sufficient).
I soldered leads onto the back of the logic board reset button so I could tie it to the reset button on the front of the case.
The USB has not been extended out the back of the case. There are cutouts available had I wanted to do so, but I don't forsee a need for it, so I didn't bother to spend the money on a USB extension cable to grant access to it.
This iMac has 320 MB of RAM installed. A 256 MB in the upper slot and a 64 MB in the lower slot. I wanted to do 512 MB, but I didn't have a low profile 256 MB SO-DIMM in stock. The iMac will be an OS X.3 Server acting as a simple file server, so I will have to see if I need to go to 512 or not. (Reports indicate you can't put 256 MB in the Rev A iMac. This is my 2nd that I am successfully using 256 MB chips in. One is maxed at 512 MB, and then this one with 320 MB. The key seems to be making sure you get chips that are 8x64 as Apple states is required. It seems many of the 256 MB SO-DIMMs on the market today are 8x32)
View from the back showing the PS/2 keyboard and mouse, and ethernet on the left. VGA on the right. I left the other cutouts open as I wanted to increase the airflow thru the case. The iMac is designed to have the heat removed via convection, and with the processor so close now to the top of the case, the heat will build up easier. The case does have 4 vent fans mounted in it to push air over the logic board and out the back. I left the cutouts open to help the fans do their job better.
Front view. The Sony drive is mac bootable. The installed hard drive is 8 GB in the center bay. There is a 2nd 3.5" drive bay available. I may connect a slave drive later for more storage space. The 8 GB drive is more like 5 after OS X Server is installed and setup, and 5 GB is rather small as a file server. The Rev A has a limit that prevents you from booting if the OS partition extends beyond the first 8 GB of space on the drive. Because of this, I opted to start with an 8 GB drive. I will probably remove it later and install a pair of 60 GB drives running a mirrored RAID. At that time I will either have to make a smaller boot partition, or look into a possible hack to boot off a larger drive.