Reference Guide
Direct from Development
Server and Infrastructure Engineering
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Dell Next Generation PowerEdge Servers: Designed for
PCIe Gen4 to Deliver Future Ready Bandwidth
The PCIe Interface
PCIe (Peripheral Component Interconnect Express) is a high-
speed bus standard interface for connecting various peripherals to
the CPU. This standard is maintained and developed by the PCI-
SIG (PCI-Special Interest Group), a group of more than 900
companies. In today’s world of servers, PCIe is primary interface
for connecting peripherals. It has numerous advantages over the
earlier standards, being faster, more robust and very flexible.
These advantages have cemented the importance of PCIe.
PCIe Gen 3 was the third major iteration of this standard. Dell
PowerEdge 14G systems were designed keeping PCIe Gen 3 in
min PCIe Gen3 can carry a bit rate of 8 Gigatransfers per second
(GT/s). After considering the overhead of the encoding scheme,
this works out to an effective delivery of 985 MB/s per lane, in each
direction. A PCIe Gen3 slot with 8 lanes (x8) can have a total
bandwidth of 7.8 GB/s.
PCIe Gen 4 is the fourth major iteration of the PCIe standard. This
generation doubles the throughput per lane to 16 GT/s. This works
out to an effective throughput of 1.97 GB/s per lane in each
direction, and 15.75GB/s for a x8 PCIe Gen4 slot. Paragraph
2nd Gen AMD EPYC 7002 and PCIe
Next Generation Dell PowerEdge servers with AMD processors are
designed for PCIe Gen4. The 2nd Generation AMD Epyc 7002
series processors support the PCIe Gen4 standard allowing for the
maximum utilization of this available bandwidth.
A single socket 2nd Gen AMD EPYC 7002 processor has 128
available PCIe Gen4 lanes for use. This allows for great flexibility
in design. 128 lanes also give plenty of bandwidth for many
peripherals to take advantage of the high core count CPUs.
Tech Note by
Mohan Rokkam
Summary
PCIe is the primary
interface for connecting
various peripherals in a
server. The Next
Generation of Dell
PowerEdge servers, and
AMD EPYC 7002
processors are designed
keeping PCIe Gen4 in mind.
PCIe Gen4 effectively
doubles the throughput
available per lane
compared to PCIe Gen3.
The Dell PowerEdge R7525
and R6525 servers have up
to 160 available PCIe Gen4
lanes maximizing available
bandwidth.