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EB7-X8G2 | Appendix A Need More PCIe Slots?
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The following image shows the Apple Profiler display when a MAC has 2 Expansion Systems connected in a “Fan-Out”
configuration.
Daisy-Chaining
This configuration offers multiple expansion slots by “sacrificing” only a single slot on the host computer. However, in this
scenario we must also dedicate one of the slots in the expansion chassis for Daisy-Chaining another chassis below it
(a.k.a Downlink). For optimal downlink performance, it is best to dedicate the chassis’ x8 slot for daisy-chaining.
In the daisy-chain configuration, successive PCIe expansion systems are added to the "end" of the PCIe expansion
hierarchy, which adds "depth" to the Local Bus by increasing the number of the logical PCI levels active in the system
configuration.
The daisy-chain configuration is therefore more popular among those who have only one available PCIe slot on the host
computer, but require additional slots downlink keeping in mind that more latency will be introduced every time we go
from one expansion chassis to the other.
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.