Liquid Cooling Loop
Water carries heat away far better than air can.
How big?Cold plates the size of a palm; pipes run all the way to the roof.
Real: What it looks like.
Keys: arrows rotate · + / − zoom · 0 reset · 1–4 views · S signal · T tour · L labels · Space spin. Models are stylised and built from code: proportions are honest, details are simplified.
What it is
Almost every watt a chip uses becomes heat. A copper cold plate pressed on the chip has tiny fins inside. Coolant flows between them and soaks up the heat.
Warm coolant goes to a coolant distribution unit (CDU), where a heat exchanger hands the heat to the building's water loop without the two liquids mixing. Cooled liquid comes back to the chip.
Why AI needs it
Modern AI chips make too much heat for fans alone. Liquid can carry thousands of times more heat than the same volume of air, which lets racks be packed far denser.
Every labeled part
- 1
Hot chip
Glows in Signal mode. The heat has to go somewhere.
- 2
Thermal paste
Fills microscopic gaps between chip and plate. Air in those gaps would block heat.
- 3
Cold plate
Copper block. X-ray to see the micro-fins inside.
- 4
Micro-fins
Lots of thin fins give the liquid lots of surface to pull heat from.
- 5
Supply (cool)
Cool coolant heading to the chip.
- 6
Return (warm)
Warm coolant heading back to be cooled.
- 7
Heat exchanger (CDU)
Stacked metal plates move heat from the server loop into the building loop. X-ray to see them.
- 8
To the facility
From here the heat goes to chillers or cooling towers on the roof.
Try it · concept lab
Where does the heat go?
Turn up the power, then change the cooling.
Chip temperature
97 °C
Status
throttling 🔥
For 100 MW of computers, the building draws 125 MW. That's 25 MW just for cooling, power conversion and lights.
Simplified model: temperature = room + power × thermal resistance. The resistances are illustrative.
Big idea: Nearly every watt becomes heat. Liquid carries it away far better than air, and every bit of building overhead costs real power.
Swap it: other ways to do the same job
Air: heat sinks + fans
Simple and familiar, but runs out of headroom around a kilowatt per chip, and the fans get loud and power-hungry.
Immersion cooling
Dunk the whole server in non-conductive fluid. Excellent cooling, awkward to service.
Dry coolers vs. evaporative towers
Towers evaporate water (efficient, thirsty); dry coolers use none but need more electricity on hot days.
Go deeper
Water or electricity?
Getting rid of heat always costs something. Cooling towers let water evaporate, which works well and uses less electricity, but a big site can use millions of gallons on a hot day. Dry coolers use almost no water, but they need more electricity, and that electricity has to come from somewhere too. Builders choose based on local weather, water and power. Neither choice is free.
Figures are rough, as of 2026.
Talk about it
- Q1
Water carries heat away far better than air. Where have you seen water cool something down faster than air?
- Q2
One way to cool uses lots of water, another uses more electricity. Which would you pick for your town, and why?
For grown-ups: there are no right answers here. Ask a question, then ask "why do you think that?" The reasons matter more than the answer.
Printable question sheet (PDF)