It was initially due to be water cooled, but the US giant switched to an air-cooled system.

As the names suggest, air-cooled machines use air to transfer heat out of their systems, and water-cooled machines use water to do this.

With fully air-conditioned coaches and air-cooled stations, it is the preferred mode of transport for the city-dwellers.

Besides the energy efficiency, liquid-cooled cards have another bonus over their air-cooled counterparts — they take up significantly less room, meaning you can fit more of them in the same amount of space.

“You can stack many more printed circuit boards in the same volume when you are using our coating, compared to if you are using conventional liquid- or air-cooled heat sinks,” the study explains.