Acoustical Design; Environmental Specifications - Dell PowerEdge R920 Technical Manual

system really needs, drawing lower fan power to help the system generate lower acoustical
noise levels than servers without such controls.

User-configurable settings: An R920 thermal control design target is to minimize the
contribution of fan power to overall system power. The default thermal setting is "DAPC"
mode, performance per watt. However, thermal settings are available for customers who
have other priorities. Available in the "iDRAC Settings" in the "System Setup Main Screen," are
"High Fan Speed Offset," "Low Fan Speed Offset," and "Maximum Air Exhaust Temperature."
For more information, see the PowerEdge R920 System Owner's Manua l on
Dell.com/Support/Manuals.
Cooling redundancy : The R920 allows continuous operation with a fan failure in the system.
Environmental specifications: Optimized thermal management makes the R920 reliable
under a wide range of operating environments as shown in the environmental specifications
outlined in Table 23. Many configurations are also compliant under expanded operating
temperature environments, but a few are not.
Acoustical design
The acoustical design of the PowerEdge R920 reflects the following:
Use: The PowerEdge R920 is appropriate for use in a data center environment and is not
intended for use in an open office space.

Adherence to Dell's high sound quality standards : Sound quality is different from sound
power level and sound pressure level in that it describes how humans respond to
annoyances in sound, like whistles, hums, etc. One of the sound quality metrics in the Dell
specification is prominence ratio of a tone, and this is listed in the table below.

Noise ramp and descent during boot-up from power off : Fan speeds hence noise levels
ramp during the boot process (from "power off" to "power on") in order to add a layer of
protection for component cooling in the case that the system were not to boot properly. In
order to keep the boot‐up process from generating high noise levels, the system fan speeds
reached during boot‐up is limited to about half of full speed.
Noise level dependencies: If acoustics is important to you, you may want to make the
following configuration choices and settings for the PowerEdge R920 because they result in
quieter operation.
iDRAC BIOS settings: Performance Per Watt (DAPC or OS) will be quieter than Max
>
Performance setting
Adjust C1E mode to "ENABLED" if Max Performance setting is selected in the BIOS and
>
the system is configured with any of the following processors: 130W, 12 core; 155W, 15
core; 155W, 10 core; or 155W, 6 core.
Configure the system with 105W processors of any core count, or 130W processors of
>
any core count, except 12 core. The system will maintain low fan speeds under most
loading conditions when operating in typical data center ambient temperatures (~25C,
77°F)
Some components cause significant but not necessarily intuitive increases in loudness when
they are installed in R920, including the following: Fusion I/O, GPU, PCIe SSD, 10Gb NIC,
CPU count, PCI card count, 10Gb NDC, HDD count and Dell PERC RAID card.
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Dell PowerEdge Technical Guide
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