Thermal And Acoustics; Thermal Design; Acoustical Design - Dell PowerEdge R940 Technical Manual

Table 14. Power supply efficiency levels
Power supply output
1100W AC
1100W DC
1600W AC
2000W AC

Thermal and acoustics

Thermal management of PowerEdge R940 delivers high performance for the right amount of cooling to components at the lowest fan
speeds across a wide range of ambient temperatures from 10°C to 35°C (50°F to 95°F) and to extended ambient temperature ranges
(see Environmental Specifications) . The benefits to you are lower fan power consumption (lower server system power and data center
power consumption) and greater acoustical versatility. The PowerEdge R940 is quiet enough to be used in an office environment in typical
and minimum configurations.

Thermal design

The thermal design of the PowerEdge R940 reflects the following:
• Optimized thermal design: The system layout is architected for optimum thermal design.
• System component placement and layout are designed to provide maximum airflow coverage to critical components with minimum
expense of fan power.
• 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
iDRAC9 BIOS setup screen. For more information, see the PowerEdge R940 Owner's Manual on
• Cooling redundancy: The R940 allow N+1 fan redundancy, allowing continuous operation with one fan failure in the system.

Acoustical design

The acoustical design of the PowerEdge R940 reflects the following:
• Versatility: The R940 saves power draw in the data center but are also quiet enough for office environment in typical and minimum
configurations. 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.
• Noise ramp and descent at boot-up 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 boot-up process as quiet as possible, the fan speed reached during boot-up 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:
26 Power, thermal, and acoustics
Class
Platinum
Platinum
Platinum
Platinum
10% 20%
89.00% 93.00%
80.00% 88.00%
87.00% 90.00%
89.00% 93.00%
50% 100%
94.50% 92.00%
91.00% 88.00%
94.00% 91.00%
94.00% 91.00%
Dell support.