Datasheet

IBM Flex System PCIe Expansion Node 4
Architecture
Figure 3 shows the architecture of the PCIe Expansion Node when connected to a compute node.
Figure 3. Architecture of the PCIe Expansion Node
The Expansion Node connects to a standard-width compute node using the interposer cable which plugs
into the expansion connector and interposer connector on the compute node and Expansion Node
respectively. This link forms a PCIe 2.0 x16 connection between the compute node and the PCIe switch in
the Expansion Node. The PCIe switch has connections to the six PCIe slots in the Expansion Node:
PCIe 2.0 x16 connections to the two full-length full-height PCIe slots
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PCIe 2.0 x8 connections to the two low-profile PCIe slots
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PCIe 2.0 x16 connectors to the two Flex System I/O expansion slots (labeled I/O 3 and I/O 4 in the
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figure).
Notes:
In compute nodes, such as the x220 and x240, I/O expansion slot 1 and 2 in the server operate at
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PCIe 3.0 speeds. However, I/O expansion slots 3 and 4 in the PCIe Expansion Node (and also the
four standard PCIe slots) operate at PCIe 2.0 speeds.
The expansion connector in the compute node is routed through processor 2. Therefore, processor 2
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must be installed in the compute node.