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PowerEdge MX7000 Direct Orthogonal Connectors
Tech Note by:
Ray Heistand
Tad Walsh
SUMMARY
The trend of increasingly higher-
power processors and DIMMs
creates challenges for traditional
midplane architectures,
particularly with regard to airflow
and cooling, high speed signal
transmission, and power
delivery.
The new PowerEdge MX7000
modular platform eliminates the
midplane and instead uses
Direct Orthogonal Connectors
for internal interconnection of
compute, storage and switch
modules.
Elimination of the midplane
greatly optimizes airflow and
enhances cooling. Signal
transmission and power delivery
are also improved by this new,
innovative design.
Modular systems (such as the Dell EMC PowerEdge M1000e blade enclosure)
integrating both compute/storage modules and switch (I/O) modules require an
intricate method of interconnection within the chassis. A traditional interconnect
architecture contains vertical compute/storage modules and horizontal switch
modules, and a midplane enabling interconnection between these modules, as
shown in Figure 1 below:
Figure 1: A traditional interconnect architecture using a midplane for interconnection of compute
and switch (I/O) modules
A traditional midplane architecture such as the above has been an effective
means of interconnect for many generations of servers, but a number of design
challenges have been apparent and need to be overcome. Airflow has been a
key challenge. Proper airflow is critical in order to ensure cooling of the
compute modules, especially with current and future systems with high-power
processors and DIMM’s. One attempt to resolve this has been to incorporate
vent holes into the midplane to allow airflow. However, due to signal and power
routing within the midplane, properly sized and effective placement of the vent
holes is not always feasible. Moreover, signal integrity (SI) may be impacted
when routing high speed signal traces long distances within the midplane. Even
the use of Low Loss PCB material (such as Megtron 6) for high speed signal
traces has limitations.
Consequently, in the development of the PowerEdge MX7000 Modular Chassis,
the elimination of the midplane was a key design goal to improve airflow and
signal integrity. To accomplish this, the implementation of Direct Orthogonal
Connectors was selected to provide the interconnection between compute
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