Pci Express - HP xw4300 Service And Technical Reference Manual

4.20.3 PCI Express

PCI Express, a hardware interconnect standard (for example, I/O slots), is a point-to-point architecture and uses a serial
data transmission protocol. A single PCI Express lane consists of four wires and is capable of transmitting 250MB in a
single direction or 500MB in both directions simultaneously. This bandwidth is not affected by what is happening on
other PCI Express buses or legacy PCI/PCI-X buses (provided that total bandwidth can be handled by the CPU and the
memory subsystem). The transmission protocol is similar to what is used for a LAN connection and contains error
correction and detection, packet addressing, and other network features.
PCI Express improves system attributes. PCI Express enables a low-power, scalable, high-bandwidth communication path
with a small number of connections (wires) compared to traditional parallel interfaces (for example, PCI).
The PCI Express I/O slots can support other PCI Express cards with lesser bus bandwidth than what is physically defined
for the slot. Use the following table to determine compatibility.
Table 4-10 PCI Express Compatibility Matrix for HP xw4300 Workstation
PCI Express x1 Slot
PCI Express x8' (x4) Slot
PCI Express x16 Slot
Mechanical Compatibility
x1 cards
x1, x4, and x8 cards
x1, x4, x8, and x16 cards
Electrical Compatibility
x1 modes
x1 and x4 modes
x1 and x16 modes
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