An example of a fully configured system with PDU-based power, five CPC drawers, and  maximum 12 PCIe+ I/O drawers is shown in Figure 2-1. An example of a BPA-based powered system with IBF, and a maximum of five CPC drawers  and 11 PCIe+ I/O drawers is shown in Figure 2-2. The key features that are used to build the system are listed in Table 2-1 on page 38. For  more information about the various configurations, see Appendix D, “Frame configurations”  on page 509. Chapter 2. Central processor complex hardware components  37 Figure 2-1 Maximum configuration, PDU-based powered system, rear view Figure 2-2 Maximum configuration, BPA-based powered system, rear view