When installing a board, remember:
Slot numbers--board slots are numbered 1, 3, 5, 7, 9, from right to left (see Figure 9-4). See "Card Cage" for an explanation of the missing even-numbered slots.
Slot functions--slot 1 should contain an I/O+ board (connects to media tray).
Aside from the requirement for the I/O+ board, all five card cage slots are equivalent.
For a more complete set of rules for configuring the system, see Appendix D, Rules for System Configuration.