Gary Testa, President and CEO of Engineered Fluids, opened his session at Mining Disrupt Miami 2021 (July 20–21, 2021) by asking who in the room was running immersion cooling. Those operators, he told the audience, were running the most profitable miners on the planet. His case rested on one idea: heat is what gates a miner's performance, and air is the least efficient way to remove it.
Bitcoin traded at $32,125 when the session was recorded. Testa's headline claim was specific: with immersion, and particularly with the company's Bitcool fluid, operators could raise hashrate 50% over stock. He said the extra hash pays off two ways. An operator with a fixed number of machines gets far more hash out of them without spending capital on more, and an operator with spare power can put all of it to work, even at a time when miners were in short supply.
air, which apparently is free and surrounds us, also happens to be the least thermally efficient way to cool anything
Gary Testa · 0:49
A Century of Liquid Cooling
Testa placed immersion in a longer history. About a hundred years earlier, he said, a German gentleman put a set of electronics in mineral oil and found he could improve their thermal efficiency by something on the order of 50%. He dated liquid cooling in high-performance computing to about 1967, crediting Cray Computer together with IBM. By the time of the Miami session, he said, more than 175 megawatts of immersion-cooled miners were running around the world, in 80 countries.
He was direct about why operators switch. Immersion is the greenest option, and he called it the least expensive, but in his account the main draw was hashrate and reliability. If an operator is going to spend the money on miners, he argued, there is no reason not to get the best performance with the highest reliability and the least maintenance. Industrial-scale miners around the world were moving to immersion for that reason, he said.
Climate, Dust and Fans
Testa called climate independence one of the most important things for operators to think about. Cheap power, he said, often sits in some of the hottest places on the planet. He named Texas as an example and said the same pattern was showing up in Latin America and Asia.
cheap power occurs oftentimes in some of the hottest locations on the planet
Gary Testa · 3:30
On reliability, he pointed to the S17. He reminded the audience of batches failing at 60 or 70 percent and said Bitcool had zero percent failure on those units. He said operators would not have to reset miners as often, if at all. Immersion also takes dust out of the picture: no cleaning miners, and no failures from machines clogged with dust and air particles. He said that matters most at remote sites and in places where skilled staff are hard to find.
Removing the fans from the miners, he said, adds an extra 10 percent straight to the bottom line, and the job takes about 30 seconds to clip the wires. He also counted the end of water use for cooling as a gain. New jurisdictions in the hottest regions, such as the Middle East, will not allow water for evaporative cooling, he said, so operators who want to deploy hundreds of megawatts there will need a method that uses none.
The Power Supply Is the Limit
Testa then turned to overclocking. A typical miner on its stock hashrate and stock power supply can deliver about 110 percent, he said, and the gating factor beyond that is the stock PSU. In his words, it is not a hash board problem. Many Engineered Fluids customers immerse the standard power supply, run the miner as hard as they can until that supply fails, and then upgrade to a larger one. A replacement PSU is typically less than $100, he said.
what you find out is that you pay for that new power supply in like six days
Gary Testa · 6:18
He tied the same logic to older hardware. A large number of S9s were coming back into the market because they could be run profitably, he said, and raising hashrate extends the useful life of mining equipment and the return on the capital spent on it.
Building for Miners That Do Not Exist Yet
The last part of his case was future-proofing. Nobody knows what the next generation of miners will look like or how fast it will run, Testa said, and immersion was already outperforming the needs of current miners by a factor of about 4 to 5x.
I can design a system for you today that will have five times the cooling capacity of anything that you can deliver today
Gary Testa · 7:04
That headroom, he argued, means an operator does not have to go back and reinvest in cooling infrastructure as miners get faster and densities rise.
Testa closed with what the company sells. Its primary intellectual property is the fluids, he said, but Engineered Fluids also designs tanks, builds turnkey systems, does fluid and hydraulic engineering, and has built complete buildings from scratch. He described the aim as lowering a customer's long-term cost as the customer takes on more of the work, and pointed attendees to booth 47 and to an 85-page immersion presentation on the company's website, available for the past three years.
The figures in the session, from the 50% hashrate gain to the zero percent S17 failure rate, are the company's own and were not tested on stage. Bitcoin was $81,514 at the time of writing, up from $32,125 when Testa spoke.