Plug & play immersion cooling. Hashrate +50%! Worth it?

Is it really worth submerging your ASICs in liquid to cool them and overclock them? In this video (in French), we explain how immersion cooling works and present turnkey kits that hold one, two or six Antminer S19-type miners. We are not immersion specialists, but we compared the available solutions and ran the numbers: does the extra hashrate make up for the price of the kit?

Video from 2023, with figures as of the end of April 2023: the prices and payback times below date from that time. See "What about today?" at the end of the article.

How immersion cooling works

You remove the ASIC's fans and submerge it completely in a tank filled with a dielectric liquid, which does not conduct electricity. The liquid, heated by the machines, flows to a cooling unit fitted with fans, then returns to the tank.

The main advantages:

• Better cooling of every component, which makes it possible to overclock the machine: you can raise its hashrate by more than 50%;
• Lower power consumption: 4 fans drawing 35 W each account for about 5% of the machine's consumption, saved straight away by removing them;
• Less vibration and more even temperatures, which should extend the life of the hardware, since it runs cooler;
• No dust and much less noise: we measure 68 decibels, compared with 80 for a stock ASIC. That makes it far better suited to a home or an office.

What the Braiins study shows

Braiins, the publisher of the Braiins OS operating system for ASICs, compared several setups for a mining farm paying 5 cents per kWh for its electricity: stock air cooling, immersion without overclocking, immersion with a moderate overclock (around 3,000 to 4,000 W) and immersion pushed to the maximum (up to 5,500 W). The most efficient setup is immersion with a first, moderate boost. The least attractive are the stock air-cooled version and the immersed version pushed to the limit.

Plug-and-play kits and their prices

The kits presented are all-in-one solutions with a built-in pump system: you plug the kit into a power socket, add the liquid and you are ready to go. They come with a one-year manufacturer's warranty.

• 1-miner kit: around €2,000 including VAT, liquid not included;
• 2-miner kit: €3,000, i.e. about €1,600 per ASIC;
• 6-miner kit: from €7,000, i.e. a little over €1,000 per ASIC. Being larger, it is shipped by sea and weighs 1,380 kg;
• Dielectric liquid: allow about €200.

The calculation: immersion or air cooling?

We ran the calculation on two models, with a boost of about 40% in immersion and consumption rising from about 3,000 W to 4,200 W per machine:

• an Antminer S19 at 100 TH/s, a big seller and inexpensive at the time, pushed to 140 TH/s;
• an Antminer S19 XP at 141 TH/s, pushed to 195 TH/s.

With electricity at 10 cents per kWh and end-of-April 2023 values, the return on investment was negative. The calculation was therefore made with Bitcoin at €56,000, for those who sell their mined coins later:

• S19 at 100 TH/s: 8 months to pay back with air cooling, 12 months in immersion, kit included;
• S19 XP: 11 months in both cases with the 1- or 2-miner kit, and the 6-miner kit even works out slightly cheaper per ASIC. A tie.

With electricity at 5 cents, the S19 at 100 TH/s goes from 21 months in the standard version to 30 months in immersion, i.e. 9 months longer.

Our view

Over the payback period, immersion cooling does not cost much more than standard cooling: it is about the same. And once the machine has paid for itself, you mine more coins thanks to the extra hashrate, with the bonus of a quiet, dust-free machine that runs cooler.

The drawbacks:

• Size: a kit takes up more space than an ASIC on its own;
• Setup takes a little longer, and day-to-day management is a bit heavier: you sometimes need to top up or change the liquid;
• The initial investment is slightly higher: instead of buying two or three ASICs, you will buy fewer.

What about today?

Kit, machine and Bitcoin prices have changed since then, and the April 2024 halving cut the block reward from 6.25 to 3.125 BTC: the payback times above are out of date. The method still applies: compare the return on investment of an air-cooled machine with that of an immersed, overclocked one, kit included, using your own figures.

To redo this calculation, use our Bitcoin mining profitability calculator and browse our Bitcoin miners. To reduce noise without going for immersion, see our DIY soundproof box method. And if you do not have room at home, consider our miner hosting.