Midi-Fridge to Cyrocooler

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Turn a dorm fridge into a Cryo CPU cooler – ÖZGÜR BASGUT (aka Efendisiz)

Hi to all Overclockers and Overclockers.com Admins!

I am a 25 year old metallurgical engineering student who lives in Istanbul, TURKEY. I’m addicted to overclocking for a long time, but for some reason I always wanted the extreme. I dealt with lots of heatsinks, fan models and lots of mods, but the best I can get is a few degrees above room temperature. This annoyed me a lot, so I decided a design a setup for sub zero cooling.

In my country, you can’t find any peltier stuff or any waterblocks in any computer shop or warehouse. So to solve this problem, I decided to make a fridge CPU cooler. Also I have to cast some copper and make some waterblocks. In other words, I have to do all the work by myself. In the beginning, I knew that this project will take lots of my time and effort, but I knew in the end it would be worth it. So let’s begin!

I bought a Prestcold 1959 model midi fridge (hope the company doesn’t exist now); this baby cost $6. I bought it from a junkyard, but it works fine.
I took out the cooling circuit and left the outer case in the junkyard.


As you can see, the ice maker part is grey in color – let me explain why. In fact, the ice maker is made from copper, but to prevent corrosion it is covered with tin (Sb) so poisonous copper oxide won’t form. But after a long time of working (this fridge is older than me), the tin layer oxidizes and forms tin oxide, which is a poor thermal conductor.

I sanded it till I reached bare copper and then painted it with two layers of anti corrosive paint. This way, thermal conductivity is enhanced. Before this mod, I could only reach -15 C; in tests after sanding, painting and some good insulation, I hit the -23 C mark – unbelievable!

The tin oxide layer
After sanding and painting

Another important point: If you are dealing with moist and wet environments, you have to take into account corrosion. In a project like this, if you are immersing copper into corrosive water, you have to protect it; if you don’t, all your effort will be for nothing when a small hole is formed on the ice maker tubing and the freon escapes from the circuit because of corrosion.

I bought a plastic container to put the ice maker in – I spent about $5 for 3 sheets of styrofoam ($1), some silicon glue ($2) and duct tape for a clean finish ($2) – here is the assembly:

The -23 C mark after insulation

First of all, always cut styrofoam with a sharp model knife or Mom will kill you for the mess you create. Take accurate measurements with a “T” ruler and cut with the support of it. After cutting the sheets, glue them with silicone to the container. Something other than silicone, which may contain solvent, will melt the styrofoam – keep this in mind! Let the glue dry overnight; after that, you can cover it with a duct tape so it won’t peel off.

Watch those fingers!
Neat and tidy
Duct tape takes the rest of the business

At this point, you can see that the ice maker is immersed in the box. This is now very important because I bent some copper tubing there; in fact, I didn’t use a pipe bender – I made it with my bare hands, but if you have one, use it. If you crack the tubing, the project goes bye bye.

After bending, I had to make a stand for the box. I made 2 wooden “T” stands for the box and screwed them to the metal case of the compressor, so here is the final product:


If you are going sub zero, you have to take extreme care about insulation. If condensation occurs on the cold parts, small droplets of water can kill your system, so BE CAREFUL when you are dealing with sub zero temperatures.

We are going sub zero people, so fasten your seat belts! What else do we need?


For a -18 C temperature, I mixed 3 liters of antifreeze with 6 liters of water; this gives me a total 9 liters – about 35% antifreeze solution. I wanted to test the antifreeze mixture and this is how it ended:


I didn’t mount the thermostat, so the fridge worked like it has no tomorrow. The result is everything froze – I hit the -28 C mark.

After I mounted the thermostat, I noticed that at the most aggressive setting, the compressor stops at the -7C mark and kicks in on 0C, which is enough for me. Maybe later I can change the thermostat to go to -20C.

In this picture, you can see my first attempt to test the my block:


This is my first design. Later I changed my design because it didn’t fit well to the socket. Now some information on my waterblocks:


You can see the two 1cm diameter main channels, but later I added one more channel in the middle to increase the inner volume. These 3 channels intercept with four 0.5cm diameter connector channels; visually, the design looks like this:


I produced eight of these blocks in case my friends may need one.
The barbs are nickel plated steel. I blocked the tips of the drill holes with metal-epoxy and also glued the barbs in the same way and covered the surface with super glue.

Block 1
Another picture

This is the block that I used for the system:

Block 2

As you can see, it is lapped and insulated with neoprene sheet. Now some information on motherboard insulation.

First you have to hack the Intel retention mechanism to keep things going. I blasted my brain on this. Finally, I decided to setup a design this way.
First remove the retention mechanism from the board:


Cut some motherboard sponge (I don’t know what this specific material is – it came out from my motherboard’s box.) Cut a hole for the socket. This first sheet is installed under the retention mechanism.


After that, you need another sheet of sponge which will fit on top of the first one; this time, cut a hole in it as big as the heatspreader only. Don’t forget the inner area, of course:


After that, we have to take care of the rear side of the motherboard. First you have to cut a piece of plexiglass the same size as the retention plate:


Drill 4 holes like this:


Then place some neoprene over it – I ran out of my neoprene sheet, so I sacrificed an old mousepad. I put 4 rubber washers on each corner for balance:


Here is the assembly – notice the blue cotton piece on my mousepad:


Damn! The screws are too long, so I drilled some holes on my mounting plate – hell of a job:


I used 20mm screws; 16mm can fit perfectly for 50mm plexiglass and 50mm neoprene. After that, my hacked mounting mechanism – I used two 9mm screw like material and 2 “O” ring screws like this:


I think this is the best way to hack a socket 478 neat and tidy:


The top retention piece is made of 6mm plexiglass and looks smooth. OK, now it’s time to insulate the tubing:


I made this insulation tubing; after making it, I put the plastic tubing inside it:


As you can imagine, blue is for inlet and red is for outlet.


It’s time to mount the sucker in place.


Don’t forget the thermal paste.


Tadaaaaa! And the block fits really well. This is the final assembly:


I know it’s big, but sometimes size does matter. Now some screen shots:

OOOPS! 1.5C – the CPU is a P4 1.8A @ 2.4 volts, the motherboard is an Asus P4PE
2987 MHz – Not Bad!
Leadtek GF4 TI 4200, 128 mb 290/540 memory settings
CPU Arithmetic Benchmark
My Final Words

This project was really hard for me – I worked on it about a year. But in the end, it was worth my effort. During this project, my dear Dad gave me lots of support and ideas – I want to thank him. But 2 months ago, he had a stroke. He survived, but is half paralyzed and lost his speech. Nowadays he is recovering, so please save your prayers for him. I want to dedicate this project to my dear father.

– ÖZGÜR BASGUT (aka Efendisiz) – Turkey

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  1. Brolloks
    Very innovative, great to see how people use creativity to meet their need, well done :)

    yeah I just wish something like that would kickass on an i7 :(
    I wonder why they coat it with tin (Sn, not Sb, by the way) when tin itself is also toxic. Unless it's just the organostannane compounds that are toxic...

    I noticed the author of the article used neoprene to insulate the block itself, could you instead substitute a thick layer of rubberized undercoating?
    It should be noted that this is from 2003, and this solution is VERY unlikely to work well on modern systems with the current heat output of CPUs and GPUs.