Installation guide
22
EMC Host Connectivity with QLogic Fibre Channel HBAs and CNAs in the Windows Environment
Installation and Configuration
PCI-X (or PCI Extended) slots increase the speed that data travels
over the bus. PCI-X slots appear identical to a 64-Bit PCI slot keyed
for 3.3v. (Refer to number 3 in Figure 2 on page 21 and Figure 3 on
page 21.) PCI-X slots are backwards compatible with 3.3v PCI
adapters and universal adapters. Inserting standard PCI adapters
into PCI-X slots will lower the bus speed, however, as they cannot
take advantage of the improved performance.
PCI-X 2.0 is the next generation of PCI-X buses. PCI-X 2.0 increases
the bus speed providing more performance for adapters. PCI-X 2.0
slots also appear identical to a 64-bit PCI slot keyed for 3.3v. (Refer to
number 3 in Figure 2 and Figure 3.) PCI-X 2.0 is also fully
backward-compatible with 3.3v PCI and PCI-X.
PCI Express (sometimes noted as PCIe) is a new bus type that uses
the existing PCI model, but implements it in a faster, serial protocol.
Because of the serial way it transmits data, the PCI Express bus slot
can be different sizes depending on the throughput it supports. PCI
Express slot speeds are expressed in "lanes" and are normally shown
as x1, x4, x8, and x16. Each type of slot are different lengths (Figure 4)
and adapter edge connectors will also have varying lengths
depending on how many lanes they require for throughput. Because
of how PCI Express slots are keyed, an x1 adapter can be inserted in
all 4 slot types as the adapter will negotiate with the slot to determine
the highest mutually supported number of lanes. However, an
adapter requiring x16 lanes will not fit into a smaller slot.
Figure 4 PCI Express slots