Sun Microsystems Fire V890 Service Manual page 231

b. Carefully rotate the board away from the power distribution board bracket.
c. Pull the power distribution board out from the system enough so that you can
disconnect the two cables still attached to the board.
6. Disconnect the following cables from the power distribution board:
a. Motherboard power cables (P7A and P7B) from the power distribution board at
connectors P7/J4 and P7/J11(MOTHERBOARD)
Chapter 6 Removing and Installing Backplanes and Cables 203