IBM F50 RS/6000 7025 - Manual (Page 205)

6. Install an additional SCSI-2 adapter or RAID adapter (if necessary) in one of the
empty PCI expansion slots. Refer to “Installing Adapters” on page 5-30 for
installation instructions; then continue to the next step.
7. Attach cables to backplane D or E.
a. When installing a hot swap backplane, connect the connector from the
EPOW cable to backplane D or E as shown.
Chapter 5. Installing Options 5-61