Release Notes

PCIe cooling strategy in PowerEdge servers
8 PCIe Card Cooling with Dell EMC PowerEdge Servers
Cards that are cooled based on temperature monitoring are called temperature controlled, while those
adapter cards that require specific airflow only are called airflow controlled. These terms are used in iDRAC
UI associated with PCIe airflow and are discussed later in this white paper.
Dell EMC-qualified cards have been thoroughly validated with PowerEdge servers and require no additional
customization from a cooling perspective. For such cards, no slot-level customization options are available to
change the airflow to them. A general fan speed increase can be used to achieve this goal by using custom
fan speed options such as fan speed offset or minimum fan speed (MFS).
Note that there is no single PCIe adapter card temperature monitoring standard. General networking cards
follow NC-SI standard, FGPA cards use PLDM specifications, and GPU card vendors like Intel, Nvidia, and
AMD have their own proprietary methods defined. PowerEdge servers must have prior understanding of the
temperature monitoring method used by the technology for them to enable closed-loop control. Hence the
idea of using a Dell EMC-qualified or -branded card is important because Dell EMC uses prior knowledge
from these cards to optimally regulate cooling to the cards.
2.3 Third-party cards and their thermal management
The automatic system cooling response for third-party cards provisions airflow based on common industry
PCIe requirements, regulating the inlet air to the card to a maximum of 55°C. The algorithm also
approximates airflow in linear foot per minute (LFM) for the card based on card power delivery expectations
for the slot (not actual card power consumption) and sets fan speeds to meet that LFM expectation. Since the
airflow delivery is based on limited information from the third-party card, it is possible that this estimated
airflow delivery may result in overcooling or undercooling of the card. Therefore, Dell EMC provides airflow
customization for third-party PCIe adapters installed in PowerEdge platforms.
2.3.1 How do I know that the system has identified a card as a third-party card?
If a card is identified as a third-party card upon installation, the following message is recorded in the LC log:
LC log message in iDRAC web UI if the system has at least one third-party PCIe adapter card