Acoustical Design - Dell PowerEdge R720 Technical Manual

inventory for system configurations. Temperature monitoring includes components such as
processors, DIMMs, chipset, the inlet air ambient, hard disk drives, NDC, and GPU.
• Open and closed loop thermal fan speed control: Open loop thermal control uses system
configuration to determine fan speed based on inlet air ambient temperature. Closed loop
thermal control method uses feedback temperatures to dynamically determine proper fan
speeds.
• User-configurable settings: With the understanding and realization that every customer has
unique set of circumstances or expectations from the system, in this generation of servers, we
have introduced limited user- configurable settings residing in the iDRAC7 BIOS setup screen. For
more information, see the
Support.Dell.com/Manuals
and Power Goals" on Dell.com.
• Cooling redundancy: The R720 and R720xd allow N+1 fan redundancy, allowing continuous
operation with one fan failure in the system.
• Environmental specifications: The optimized thermal management makes the R720 and R720xd
reliable under a wide range of operating environments as shown in Table 31.

Acoustical design

The acoustical design of the PowerEdge R720 and R720xd reflect the following:
• Versatility: The R720 and R720xd save you power draw in the data center but are also quiet
enough for office environment in typical and minimum configurations. Compare the values for
LpA in Table 21 and Table 22 for these configurations, and note that they are lower than ambient
measurements of typical office environments. You may find that the system is sufficiently quiet
where the sound it emits blends into the environment.
• 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 and hums. One of the sound quality metrics in the Dell specification is prominence
ratio of a tone, which is listed in Table 21 and Table 22.
• Noise ramp and descent at bootup from power off: Fan speeds and 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 event that the system were not to boot properly. In order to keep the
bootup process as quiet as possible, the fan speed reached during bootup is limited to about half
of full speed.
• Noise level dependencies: If acoustics is important to you, several configuration choices and
settings are important to consider:
For lower acoustical output, use a small number of lower rotational- speed SATA hard drives,
nearline SAS hard drives, or non- rotational devices like SSDs. 15k hard drives generate more
acoustic noise than that of lower rotational- speed hard drives, and noise increases with
number of hard drives.
Fan speeds and noise may increase from baseline factory configurations if certain profiles are
changed by the user or the system configurations are updated. The following is a list of items
that impact fan speeds and acoustical output:
iDRAC7 BIOS settings: Performance Per Watt (DAPC or OS) may be quieter than
>
Performance or Dense Configuration (iDRAC Settings > Thermal > Max. Exhaust
Temperature or Fan speed offset).
The quantity and type of PCIe cards installed: This affects overall system acoustics.
>
Installation of more than two PCIe cards results in an increase in overall system acoustics.
PowerEdge R720 and R720xd Technical Guide
39
PowerEdge R720 and R720xd Owner's Manual
and "Advanced Thermal Control: Optimizing across Environments
on