Answer
Far less than its rating. IBM publishes two different numbers for the same machine and they are not close.
The rated maximum is what the machine is permitted to pull, and it is the figure an electrician and an inspector work from. The measured figure comes from IBM's own filings under EU Regulation 2019/424, where IBM tests a high-end and a low-end configuration of each machine type and reports idle and maximum power for both.
Across the Power 9 family the measured maximum runs between 22 and 55 percent of the rated maximum. A two-socket Power S924 rated at 2,750 W measures just under 965 W flat out. A Power S914 rated at 1,600 W measures 350.5 W.
The practical rule that follows:
- Size the circuit to the rated maximum, because that is what codes and inspection require.
- Size the UPS and the cooling budget to the measured maximum plus a real margin, because sizing those to the rating buys capacity the machine will never ask for.
- Get your own measurement from a metered rack PDU once the machine is installed, because your configuration decides where inside the tested range it actually sits.