Release Notes

Introduction
5 PCIe Card Cooling with Dell EMC PowerEdge Servers
1 Introduction
PowerEdge servers have the cooling capacity to support a broad array of PCIe adapters. These servers use
customized fans, airflow shrouding, and optimized system topologies to maximize airflow that is provided to
PCIe slots. The design also ensures the temperature of the air that is delivered to the PCIe cards is at or
below industry requirements.
Embedded within Dell EMC’s industry-leading iDRAC systems management features, an intelligent thermal
controls algorithm is used to reduce fan power consumption and acoustics without compromising component
reliability or performance. This algorithm uses several temperature monitoring sensors and knowledge of the
installed system hardware configuration to achieve higher efficiency.
As a feature of Dell EMC’s thermal control architecture, your specific hardware configuration determines the
baseline fan speed. The fan speed is set to cool components that do not have temperature monitoring.
Fan speeds may never go below this level unless the inlet ambient temperature or system configuration
changes. When inlet ambient temperature or hardware changes occur, the thermal control uses open-loop
control algorithms to determine when to increase fan speeds to cool components whose temperatures are not
monitored. The PCIe card responses that are described in this white paper can increase fan speeds above
the baseline.
PCIe adapter vendors develop cards with a general 55° C inlet card temperature limit, or 45° C for a few
adapters, and define the airflow cooling requirement for the card in terms of linear feet per minute (LFM). The
vendors also ensure that the card cooling boundary conditions are within server vendor expectations and
aligned with the PCIe cooling specifications of the server vendor. Recent updates to PCI-SIG (industry
standard for PCIe devices) allow a card to specify a cooling tier, called MaxTherm level. Each level
represents the LFM requirement for the card as a function of inlet air temperature to the PCIe card. When the
vendors adopt this updated specification and report MaxTherm levels, Dell EMC’s thermal controls algorithm
can read that information from the third-party PCIe cards and provide the required LFM.
This document provides detailed guidelines on how PowerEdge servers manage airflow to third-party PCIe
cards and airflow customization options where applicable.