Ones Stop Systems
EB7-X8G2-RAS | 8
Appendix A Need More PCIe Slots?
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8.2 The Fan-Out Configuration
The Fan Out addition to the PCI bus hierarchy is at the "peer" level of other existing expansion buses, thus adding "breadth" to the PCI bus
hierarchy, since these buses will be at the same hierarchical level within the system configuration.
You must ensure that you have the corresponding PCIe to PCIe Expansion System, or chassis to connect with your
host card to support your desired configuration.
In this configuration, you have fewer “Toll Booths” to pass through; therefore the latency is shorter, however you “sacrifice” a PCIe slot in the
host computer for each added chassis.
For clarification, it is necessary to understand that the amount of latency caused by a PCIe switch (or a PCIe-to-
PCI bridge built into some 3
rd
Party PCIe cards) is negligible (“nanoseconds”) and will not produce any visible
effect on most systems. It is only mentioned here because of certain specialized configurations involving unique
PCIe cards with special software drivers. The total number of logical buses that the data must pass through
COULD make a difference. See
Chapter 5 Troubleshooting
for more information if you suspect this could be an
issue with one of your specialty PCIe cards.
Verify your configuration
Before you start installing your PCIe cards (refer to
Chapter 4 Install PCIe Cards for
more information), you should confirm that everything is in
proper working order. Refer to
Chapter 3 Verify Installation
for guidance in verifying the proper installation of your Expansion System. For
example, the following image shows the division within the Windows Device Manager display between two Expansion Systems connected in a
“Fan-Out” configuration. In this case each expansion chassis offers only two slots of expansion.
