Lessons · Lesson 2 of 6
Where does the power go?
Why a building with 10 MW of chips asks the grid for more than 10 MW.
Not all power reaches the chips
For every unit of electricity the chips use, the building needs some more: for fans, pumps and chillers that remove heat, and for losses in the electrical equipment.
Engineers sum this up in one number, PUE (power usage effectiveness): total power ÷ chip power. A PUE of 1.0 would mean zero overhead. Lower is better.
Play with the weather and the cooling
Cool outside air can do much of the work for free. Hot weather makes the chillers work harder.
Liquid cooling carries heat straight off the chips in water-like coolant, which takes far less energy than blowing air around. Try both, and slide the temperature.
Quick check
A data center has a PUE of 1.2. What does that mean?
- The chips get 20% more power than they need
- For every 1 kW the chips use, the building uses 1.2 kW in total
- The building is 120% efficient
Show the answer
For every 1 kW the chips use, the building uses 1.2 kW in total. PUE is total power divided by chip (IT) power. 1.2 means 0.2 kW of cooling and losses for every 1 kW of IT.