Sensor Equipment has created what may well be the coolest Raspberry Pi 4 around — literally, thanks to an inverted heatsink dunked in liquid nitrogen as a coolant.
The Raspberry Pi 4 Model B family is the most powerful single-board computer the Raspberry Pi Foundation has yet designed, but that power comes at a cost: It can run surprisingly hot. Since launch, a series of firmware updates have improved efficiency and reduced overall temperatures — but third-party cooling add-ons remain popular.
Sensor Equipment's CooliPi is just such an add-on. A two-part design formed from a 3D-printed case with a CNC-milled and extremely large aluminium heatsink, the CooliPi offers passive cooling — or, with the addition of an optional adapter, active cooling with a fan.
As a video released by Sensor Equipment's Lada Myslik shows, though, there's another option: Inverting the board and dunking the fins of the heatsink directly into liquid nitrogen. In doing so, Myslik discovered a minor bug in the way the Raspberry Pi OS — and, potentially, other operating systems for the Raspberry Pi — report the temperature of the system-on-chip: If it goes below the freezing point of water, the figure will wrap around.
"I've devised a method for slowing the initial heating of the cooled board," Myslik tells us in an email, for those who want to test their own systems at home but don't have access to liquid nitrogen as a coolant. "Put it upside down as seen on my LN2 video, pour some water under the fins, let it freeze in a fridge to -18˚C if possible and then boot up. It'd look funny, having a Raspberry Pi 4 between the peas and carrots, but we have too much of them in a fridge so that I can't do this test myself at the moment!"