What to Do with Your Old Desktop Mac


Jan 8, 2014
Or, How To make use of obsolete hardware.

Tools required:
Screwdrivers of various sizes
Angle grinder
Mini grinder (Dremel type thing)
Cordless drill/driver
Wire cutters
Adjustable pliers
Soldering iron and solder
Hot glue gun and sticks
Stanley Knife

Other useful stuff:
Spray paint and somewhere well ventilated
Box of random computer bits that you've not thrown away because 'it'll be useful for something eventually'
Large bin
Patient wife

This project started some months ago when flicking through computers and parts on ebay; I spotted a mid nineties iMac G3, in bondi blue, up for a fiver and no bids

I can't think of anyone else who would drive for more than two hours to buy a broken computer, but I was on a mission. The guy said that it could be made to work again, just needed some memory and a hard drive... That didn't fit into my plans at all.

Initial case mods

In my excitement I forgot to take any pictures of the dismantling process, but that's probably a good thing, as after carefully removing the plastic shell, it got messy.
All the old hardware was binned, and I was left with a rather floppy metal chassis and six plastic pieces that form the case. All the other bits, wires, switches etc were carefully bagged and boxed until needed.
I had in my shed an ancient (80's?) PC case, made of real thick, heavy steel; it was a gift from a local freecycler. My son's complete mid tower PC weighs as much as this empty box (including 24" monitor, probably). The motherboard tray and back panel were cut from the case using an angle grinder. Don't forget to wear eye protection when using power tools. And gloves too, if you're a bit girly.

What was the top edge of the motherboard tray was already formed into a 90 degree angle. Holes were drilled to line up with the holes in the chassis, and secured with M4 bolts and nuts, with an extra nut between as a spacer.
The other edge was flat, but rather than try and bend the whole length, I marked and removed the tray and made a couple of grinder cuts inwards near the top and bottom edge, then bent and drilled the section between the cut and the top / bottom. All bolted up, the rest of the tray sits nicely against the chassis. The back piece is fixed to the chassis bottom with a mixture of screw and bent metal. Just before doing that, I cut some of the chassis bottom out, in what looked like roughly the right place.

At this point, I didn't know what other metalwork was required until I had gathered the hardware, but there was plenty to faff with in the meantime.

Preliminary design decisions

I considered keeping the original fan in place, and making a duct to channel the moving air toward the motherboard. Cardboard prototype:

The off-white panel at the back used to be where all the power supply components were circuited up. There is another panel that fits the other (near) side, which held all the components for the CRT display. I wanted to reuse both panels in their original position, so that meant two solid afternoons with a soldering iron, removing everything from both boards. I didn't count, but from the component numbering on the PCB I estimate about four or five hundred bits were stripped in all.
The duct idea had been dismissed. I tested the duct with the fan in place and running, and wow, huge airspeed from that narrow duct outlet. But also huge noise from the fan in it's housing. I tried to get round this by making a bracket slightly larger than the fan so I could secure it vertically with silicone. Turns out isolating the fan from everything doesn't solve the noise issue when the fan itself is loud. Will work out cooling later. I had also started working out where everything was going to go, and where wires would run etc. The PSU would be fixed upright behind the screen, hopefully. If not, I had a plan B. While I was waiting for deliveries, I got bored and spray painted it black.

The GPU had arrived. It looks like it will fit. Note how easily the paint chips off.


This project is more of a proof of concept than ultra-gaming. The choice of components reflects that; old, used, low-end, low-power, and compact, but most importantly, CHEAP!

Motherboard: ASRock H61M-VS £10
CPU: Intel Pentium G620 £19
GPU: OEM? Nvidia GT240 £11
All from ebay, prices include delivery cost.

The motherboard arrived with some minor damage to the CPU socket (no cover), other than that, those three items were in very good condition. I used a magnifying glass, a needle and balls of iron to straighten up the seven or eight bent pins, then checked their alignment by holding it to reflect a bright light and comparing the intensity of the reflection from the rows of pins. Looks good. The case wasn't ready yet so I taped the plastic bit from a battery blister pack across the open socket and packed it away safely.

Memory: 2GB Mushkin Black 1600 - borrowed, but I will be upgrading to 2x2GB dual channel, which should improve performance.

PSU and Monitor: These I got from a local computer recycling/refurbishment company, traded for some non-functioning computer equipment. The monitor is a basic 15" 1024x768 LCD, and it works well enough. The PSU is a 300w FSP 80+ Bronze mATX unit, and is better than I was expecting for basically nothing.

HDD: 80GB SATA II 2.5" drive. A spare one that was just sat gathering dust.

Other bits: 140mm coolermaster fan. RJ45 socket. LEDs and resistors. Audio amplifier. Probably another £20.

Design part 2: Headscratching

First thing I did was download the manual for the motherboard and print the page with the layout diagram at full scale, this took a little trial and error to get the size right, and blu-tac'd it to the motherboard tray. Now I have a reference point to work from.

After measuring the gap from the back of the screen to the back of the motherboard tray, I find the EMF shield is too big by about 5mm and would block the fan. It's PSU placement plan B time. So, I chopped a chunk out of the bottom of the tray so the PSU would sit on the chassis, below the motherboard. Dropped it in and had a look at it - something's not right, but I can't put my finger on it. Took me a while to figure out, but I realised that the audio cable would be passing through the PSU fan... oh, ah heck. Time for a sit down and a good think.

Something had to give, and it was the optical drive. I couldn't sit the PSU at the back of the case, it would fall over all the time, so the only place it could go was the drive caddy at the bottom.

The white thing to the left of the PSU is a molex to 3 pin fan splitter, fixed to the underside of the tray with one of the original motherboard screws.
Bonus advantages to this position: The PSU is in the middle of the four rubber feet, so it falling over isn't even possible. And I don't have to find a slim DVD drive with the open button in the right place to line up with the one on the drive cover. A little research told me I can install windows from a USB hard drive, I have a spare external drive I can use for that. And the button on the redundant drive cover? I could make use of that as the power switch for the screen, which has to be manually pressed to turn it on.

LCD mods

It's a basic monitor with speakers, made by Teco (?), with a plastic case that was very easy to dismantle; five screws and it popped apart with minimal screwdriver leverage. Now I had me with a steel-framed screen that has four fixing lugs attached, so far so good.
Flipped it over, normal 3-pin power socket and, dammit, fitted VGA cable. This is going to be a cut and shut. Unscrewed the EMF shield and carefully unplugged the exposed cables from their sockets, then put the shield back and bubblewrapped the screen for now. The VGA cable was over five feet long, I needed it to be about a foot, maximum. I cut the cable about two inches past the choke on each end, opened and spread the wires within so I could solder them all back together. That done, I wrapped a square of electrical tape onto itself over each join, then a heap of tape over the lot. It's not pretty:

The board with the controls will fit behind the drive cover, but not as it was; I desoldered the power switch and replaced it with a vertically mounted switch I found in the bits box. It's still attached to a PCB, but with the copper tracks and edges ground off. Now it was facing the same way as the volume wheel. And a big blob of hot glue behind it for support. The power light on the PCB lines up perfectly with the translucent blue power button on the drive cover, another bonus. Small problem, it's too big for the space behind the drive cover, so the headphone jack end of the PCB was carefully ripped off with wire cutters, and then ground down with a Dremel substitute to prevent shorts. The other end was also shaped to fit around the front of the metal drive caddy and the long front edge was ground to match the curve of the drive cover:

The drive cover itself needed a hole for the volume wheel, which was another fiddly job for the Dremel-type tool. Yes, it could have been a little neater.

It's fixed to the drive cover with hot glue and some bits of stiff plastic for extra strength. And some more hot glue.

The screen was slightly larger than the old CRT, and so I needed to grind away some plastic 'fins' on the inside of the plastic front panel and a couple of fixing posts that weren't going to be reused. The four fixing lugs on the screen frame had to be bent upwards with pliers so it would drop into the gap, and small self-tapping screws into the stiffening ribs on either side secure it in place.

As you can clearly see here (ha! not with my photography skills), a square peg does not fit in a round hole. I wish I had saved the original CRT just so I could mould a sheet of perspex over it to fill the gaps between the curved plastic and the flat screen. Isn't hindsight brilliant...

PSU mods

The PSU hasn't escaped the tools. Opened it up, and it looked mint - shame I was going to ruin it. First thing was the power switch - it wasn't needed and it wasn't going to be accessible. Desoldered the switch and connected the wires together. The power cable wouldn't fit, so I had a look at some prices before deciding I wasn't going to pay a fiver for a right-angle power cable, when I had loads of straight ones and a Stanley Knife. A couple of cuts into the moulded plug and strain relief part, and a bit of tape to hold it down, and I had a right angle power lead that fitted nicely. After testing I had to open the PSU again and flip the fan over to improve airflow through the case.

Other mods

Thanks to Apple Inc's proprietary connector nonsense, there was a few things that needed altering to make it connect to the new hardware. The front Headphone and mic sockets had to be trimmed off the PCB with the power switch and LED. In their place was a cut-down front panel from who knows where, which had it's own wiring with a standard motherboard connector. Lots more hot glue here.


A quick placement check revealed the front panel wouldn't fit because of all the hot glue.

The obvious solution was to chop the vertical plastic piece out, (to the left of the headphone and mic sockets).
At this point I noticed the power LED was a two colour one, so with a little bit of hackery I attached the positive of the PWR and HDD motherboard header wires to the anodes and both negatives to the LED cathode.

The rear panel had holes for the network and USB sockets, and some more that I wasn't going to use at this time. There was a couple of brackets with pre-drilled screw holes on the inside of the darker blue panel, so I cut a strip of steel from one of the bits I had removed at the start of the build, drilled holes and screwed it to the brackets. The modular RJ45 socket had a plastic clip designed to fix it to a faceplate, this slipped nicely over the strip of steel and was secured with lashings of hot glue. The other end of that cat5e cable ends with a standard RJ45 plug into the motherboard. I had some left over from cabling the whole house, and a bag of plugs and the crimping tool.

The double USB port was taken from the same front panel as the headphone and mic sockets, and had standard wiring already attached. A slice of silicone finger* is wedged under the PCB to prevent shorts on the steel, and it's also covered in hot glue. At this point, I'm running out of glue sticks.
The power socket at the back of the case is attached to the side panel, so when removing components I kept the ones I wanted to reuse - the connector from the mains socket and the glass fuse. I connected two power leads from here to supply the PSU and LCD.
During testing I found the sound needed amplification, I could only hear it when my ear was millimetres from the speaker and there was no background noise. Maplins helpfully sorted me out with a 1 watt amplifier kit, which was ridiculously easy to put together.

+ ten minutes, including waiting for the soldering iron to warm up and tidying up after =

A quick test, and it works! Set the gain on the amp so that the volume is adjusted by the wheel on the front.

I couldn't find a suitable box so I wrapped the bottom and sides in tape, made the input and speaker connections permanent and roughly stuffed the lot onto the hole next to the PSU.

Custom Lighting

I had plenty of LEDs and resistors, and had been shopping for more glue sticks, so I made my own lighting. Molex fan splitters were useful here for connecting an LED circuit that was split across different parts, such as the side panels. Each LED is wired in parallel with its own 47ohm (IIRC) resistor

There are four yellow/green LEDs in the bottom tray, two white LEDs on each side panel, and twelve white LEDs behind the screen. The mesh part of the chassis is just the right size for wedging these LEDs in.

I connected them up to the PSU to test the lighting, and after closing a few light leaks with black tape, I was more than happy with the result.


Full component test


Because I'd rather find out now if anything isn't working. Only I didn't connect the twelve LEDs attached to the chassis - I found out later that they needed to be connected to different molex because it was too much for one to supply when everything else was running as well.
Powered up, and I can get into the BIOS, everything seems okay.


Or, something about quarts and pint pots.
I wasn't entirely happy with the rough edges of the steel, so some grommet strip was applied where wires could potentially short out. Various lengths of string and pointy sticks were used to get the cables to go around or through to where they needed to be. I had a small panic about whether the 24-pin and 4-pin power connectors would reach, in the end they did, but only just. The printed diagram meant I could work without worrying about damaging anything more than the paintwork.

The front end, wired and ready:

The white thing dangling on its wire was supposed to fit into a space moulded into the front plastic panel, but I forgot, and now it won't fit because the chassis is right behind it when it's all firmly screwed together. Instead, I removed the LED from its rubber housing and it is now fixed at the back of the case, next to the shiny power socket. When the power button is pressed there's a brief flash or red from the mains lead area, the LED is connected to the beep speaker header.
I didn't get the heatsink on properly first time around, but that was easily rectified.
It quickly got very cramped in the back:

Now it's almost ready for the outer shell. The drive cover is fixed to the front trim with, you guessed it, more hot glue.



The 140mm fan on top is fixed to a stiff wire frame that sits across the top of the motherboard tray and both sides. I had to move the hard drive flat against the other side, but the fan was catching the graphics card. So, I grabbed the wire cutters, girded my loins and snipped the corner off it. That may have voided the warranty slightly, but the fan spins freely now.

After a bit of faffing about with the electric spaghetti, the plastics went on and it's ready to test drive. The plastics just clip together, but there are two meaty screws in each side to hold it all together when carrying it by the inbuilt-in handle. I don't carry it by just the handle though, even though it weighs about the same as the original, it is close to twenty years old and who knows how many hot/cold cycles it's been through.

Power on, windows installed, plus drivers etc. Disc image saved on USB hard drive, for when it all goes 'wibble'. Not if. When.




Apart from a retro white keyboard and mouse that I haven't even started looking for yet, it is finished. Everything works as I imagined it would, and I'm rather pleased with how it turned out. The power LED flickers nicely between red and green. The gap around the screen I can live with because the 'Auto Adjust' button for the screen (on the PCB two inches below) is accessible via a pencil. Performance is mostly rubbish, but it runs minecraft (maxed) and 720p youtubes well enough, and that's what it will be used for 99% of the time. It's a great piece of design, and now it lives on.

I have learned a great deal during the course of this project, mostly 'how to not dremelise your fingers' and 'getting plastic shit in your eyes does sting a bit'. Don't do what I did, i'm f****** hardcore.
There's a few things I would do differently on the next custom build: Better quality paint. Higher spec parts, without compromising compactness too much. Reverse-engineer a server PSU, maybe (the dimensions would have been perfect here, but couldn't find one at the right price. Or in the right country.) I might even invest in a pair of safety specs ;)


A few honourable mentions as it's the end: the guys at Aspire, thanks again :D. My wife, for putting up with my shit. And you lovely people at Toms, without whose combined knowledge I would still be trying to load a floppy disk into a toaster to give it wifi. Thankyou :)

*silicone fingers, custom made anti-vibration dampers.


To make silicone fingers you will need:

A rubber glove, latex gloves are ideal
A silicone cartridge and cartridge gun ( I can happily recommend the following: http://www.toolstation.com/shop/Adhesives+Sealants/General+Sealants/SX+Contractors+HMA+Multi+Purpose+Silicone+300ml+Clear/d180/sd2350/p13861 and http://www.toolstation.com/shop/Adhesives+Sealants/Sealant+Tools/Standard+Applicator+Gun+425ml/d180/sd3177/p52047)
Stanley Knife or similar

Remove cartridge seal with Stanley Knife, cut nozzle about halfway down to increase flow rate. Fill fingers of glove with silicone, keeping the tip of the nozzle in the expanding silicone prevents major air bubbles. Flatten into rough rectangles and leave to set.
When it is set, and the surface is firm all over, remove the rubber glove. When fully cured (72h indoors, a week+ in a cold shed), your silicone fingers can be cut to size. Full finger widths can be cut with a Stanley Knife, but use a piece of board to hold it down so your fingers are well away from the blade. Slices of silicone finger can be used anywhere there's a gap between two things that are rubbing against each other - HDD/DVD mountings, case fans, under the case feet on the desk.
You can also use this method to make a full silicone hand on a stick, for long-range slaps ;)