Specifications

29 PowerEdge R420 Technical Guide
 Multiple sensors are monitored for thermal feedback control: The PowerEdge R420
dynamically controls system cooling fan speed based on responses from component
temperature sensors, including processors, hard disk drives, DIMMs, storage cards and the
inlet ambient temperature. Thermal control detects and responds to hardware configuration.
Thermal management adjusts cooling according to what the system really needs, and draws
lower fan power draw and generates lower acoustical noise levels than servers without such
controls.
 User-configurable settings: An R420 thermal control design target is to minimize the
contribution of fan power to overall system power. However, with the understanding and
realization that every customer has a unique set of circumstances or expectations of the
system, in this generation of servers, we are introducing limited user-configurable settings in
the iDRAC7 BIOS setup screen. For more information, see the Dell PowerEdge R420 Systems
Owner’s Manual on Dell.com/Support/Manuals and “Advanced Thermal Control: Optimizing
across Environments and Power Goals” on Dell.com/PowerEdge.
 Fan fault tolerance: The R420 allows continuous operation with a motor failure in the
system. The base configuration of the R420 has four fans. Additional fans are needed when
using redundant power supplies and a second processor. The fault tolerance feature allows
one motor fan to fail at a time, allowing a fan replacement within 360 hours of a fan failure.
 Environmental specifications: The optimized thermal management makes the R420 reliable
under a wide range of operating environments as shown in the environmental specifications
in Table 26. Many configurations are also compliant under expanded operating temperature
environments, but a few are not.
Acoustical design
The acoustical design of the PowerEdge R420 reflects the following:
 Versatility: The PowerEdge R420 saves you power draw in the data center, but it also is quiet
enough for the office environment in typical and minimum configurations. Compare the
values for LpA in Table 18 for these configurations, and note that they are lower than ambient
measurements of typical office environments.
 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 18.
 Noise ramp and descent during 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 case that the system were not to boot properly. To keep
bootup 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, you may want to make the
following configuration choices and settings for the PowerEdge R420 for quieter operation:
— In the BIOS, select the power-optimized DAPC rather than performance-optimized for the
system thermal profile
— Turn hot spare feature off in PSU
— Since hard drive noise is highly dependent on spindle speed, the 7200-rpm SATA hard drive
will have the quietest hard drive operation
However, some components cause significant but not necessarily intuitive increases in loudness
when they are installed in the R420. Contributors to acoustical output can include: