IBM xSeries 346 Hardware Maintenance Manual And Troubleshooting Manual page 18

v If the operating system stops functioning, you can press and hold the
v The service processor can turn off the server as an automatic response to a
v You can turn off the server through a request from the service processor.
8
xSeries 346 Types 8840 and 1880: Hardware Maintenance Manual and Troubleshooting Guide
power-control button for more than 4 seconds to turn off the server.
critical system failure.