Specifications
Chapter 2. Architecture and technical overview 91
General rule for the 12X IO Drawer configuration
To optimize performance and distribute workload, use as many multiple GX++ buses as
possible. Figure 2-33 shows several examples of a 12X IO Drawer configuration.
Figure 2-33 12X IO Drawer configuration
Supported 12X cable length for PCI-DDR 12X Expansion Drawer
Each #5796 drawer requires one Dual Port PCI DDR 12X Channel Adapter, either Short Run
(#6446) or Long Run (#6457). The choice of adapters is dependent on the distance to the
next 12X Channel connection in the loop, either to another I/O drawer or to the system unit.
Table 2-32 identifies the supported cable lengths for each 12X channel adapter. I/O drawers
containing the short range adapter can be mixed in a single loop with I/O drawers containing
the long range adapter. In Table 2-32, a Yes indicates that the 12X cable identified in that
column can be used to connect the drawer configuration identified to the left. A No means that
it cannot be used.
Table 2-32 Supported 12X cable lengths
2.10.5 12X I/O Drawer PCIe and PCI-DDR 12X Expansion Drawer SPCN cabling
System Power Control Network (SPCN) is used to control and monitor the status of power
and cooling within the I/O drawer.
SPCN cables connect all ac-powered expansion units (Figure 2-34 on page 92):
1. Start at SPCN 0 (T1) of the first (top) CEC enclosure to J15 (T1) of the first expansion unit.
2. Cable all units from J16 (T2) of the previous unit to J15 (T1) of the next unit.
Connection type 12X cable options
0.6 m 1.5 m 3.0 m 8.0 m
#5796 to #5796 with #6446 in both drawers Yes Yes No No
#5796 with #6446 adapter to #5796 with #6457 adapter Yes Yes Yes No
#5796 to #5796 with #6457 adapter in both drawers Yes Yes Yes Yes
#5796 with #6446 adapter to system unit No Yes Yes No
#5796 with #6457 adapter to system unit No Yes Yes Yes
PCIe
770
780
PCIe
770
780
PCIe
770
780
770
780
770
780
PCI-X
PCIe
770
780
PCIe
PCIe
770
780
PCIe
PCIe
770
780
PCIe
One PCIe I/O Drawer
Two PCIe I/O Drawers
Three PCIe I/O Drawer
Four PCIe I/O Drawer