Half-Hour Hacks – Watercooled Antminer U2

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The Antminer U2.

Cryptocurrency is a pretty hot topic lately, and can be a profitable endeavour for some. For others, like myself, it’s a fun hobby. Something to leave running in the background and tinker with from time to time. After a few weeks of GPU mining Dogecoin on my laptop with middling results, I decided to drop $30 on an Antminer U2 on eBay.

Initially, I was able to get a stable rate of 2.2GH/s by basic overclocking. Any higher and the gains in hash rate were offset by excessive hardware errors. To this end, I decided to explore the possibilities of enhanced cooling.

The Antminer’s design is neat and tidy, with a single aluminium heatsink. I came up with a simple concept – rather than build a replacement heatsink with a waterpump and radiator, why not just take advantage of the stock heatsink and turn it into an open reservoir for ice cold water? As long as the miner isn’t bumped and the design is sealed properly, risk of water damage is minor. In the worst case, I accidentally spill water everywhere, ruining my old broken laptop and a $30 miner ASIC that isn’t fast enough to be profitable anyway.

My plan was simple – seal the boltholes holding the heatsink to the board, and then attach four walls to the heatsink to hold water. I used 5-minute epoxy first to seal the holes, before using some sandpaper to roughen the edges of the heatsink to help bond the walls later. I also covered the solder joints for the USB connector to avoid my new walls shorting anything out.

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Sealing the heatsink and insulating solder joints.

Next, I grabbed some scrap aluminium plate and cut out some walls for the four sides of the heatsink. This was done quick and dirty with a hacksaw, but using a lasercutter or a 3D printer to do this project would be really great.

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Aluminium plate was used to create new walls for the heatsink, to hold water.

I wanted to start and finish this in half an hour, so I got inventive. After quickly roughing up the original heatsink with some sandpaper, the new walls were tacked in place with superglue, before applying 5-minute epoxy to seal the edges. More superglue was dripped into the edges of the heatsink to ensure a watertight seal between the walls and the original heatsink.

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Gluing the walls to the heatsink.

After waiting for the epoxy to dry and tentatively testing it for water tightness, it was ready to go. The reservoir was topped off with water and an icecube, and CGminer fired up.

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The Antminer U2 back in operation.

Thus far, the U2 has been stable at 2.2GH/s both with and without watercooling. Over the coming days, overclocking will be attempted to see if 2.5GH/s is within reach.

While this project (or a single Antminer) is completely unprofitable as far as mining goes, it’s a bit of fun to experiment with. Leave your own mining mods in the comments!

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