Lenovo ThinkSystem DS Series Hardware Installation And Maintenance Manual page 41

Dual PSUs provide redundant power for the 5U system: if one PSU fails, the other keeps the system running while
you replace the faulty module. PSUs are hot-swappable. Replacement of a PSU can be performed while the
enclosure is running, but the procedure must be completed within two minutes of the removal of the defective
module. Verify that you have a replacement PSU on hand before removing the defective module.
Power supply unit – 5U enclosures 41