Dell PowerEdge R720 Technical Manual page 41

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Comprehensive thermal management: The thermal control system regulates the fan speed based on
several different responses from all system-component temperature sensors, as well as 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
PowerEdge R720 and R720xd Owner's Manual
Control: Optimizing across Environments 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.
Using a GPU card: This results in an increase in overall system acoustics.
>
PCIe controller-based SSD drives: Drives such as Express flash drives and Fusion-io cards
>
require greater airflow for cooling, and result in significantly higher noise levels.
Systems with an H310 PERC: This configuration may be quieter than those with an H710
>
PERC with battery backup. However, higher noise levels result when a system is
configured as non-RAID.
PowerEdge R720 and R720xd Technical Guide
41
on Dell.com/Support/Manuals and "Advanced Thermal