White Papers

Dell PowerEdge VRTX Acoustics and Thermals
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Executive summary
Thermals and acoustics are key design areas of the Dell™ PowerEdge™ VRTX. Although delivery to the
acoustical sensitivity of an open office layout is the primary focus of this white paper, several other thermal
and acoustical design features are also discussed. These features include configuration-based acoustics, an
Enhanced Acoustics option that enables users to maintain a quiet environment even with high-power
processors, an Enhanced Cooling Mode (ECM) that provides for greater cooling capacity when desired, and
fan speed offsets. Understanding these features can help users optimize the system for specific use cases in
their particular environments.
Acoustical choices
Introduction
PowerEdge VRTX has been designed for open office acoustics. The host chassis has been mechanically
designed to damp the baseline acoustical signature with respect to the wide range of supported power loads
and hard disk drives (HDDs). Dell’s patent-pending blower module delivers a smooth sound that is absent of
tones (buzzes, hums, whistles, etc.) and yields a low acoustic intensity per delivered airflow. The resulting
sound is generally masked by that of normal office air conditioning or conference room conversations.
The lowest acoustical values that PowerEdge VRTX will reach are represented in Table 1 below. Dell focuses
on sound quality in addition to sound power level and sound pressure level. At LpA=36 dBA and no prominent
tones (see descriptions of these metrics in Table 1), the sound is generally appropriate for an open office
layout (see Table 2,
Sound quality describes how disturbing or pleasing a sound is interpreted, and Dell references a number of
psychacoustical metrics and thresholds in delivering to it. Tone prominence is one such metric. Sound power
and sound pressure levels increase with greater populations or higher utilization, while sound quality remains
good even as the frequency content changes. Acoustical changes with components or utilization are
described in the following section. More extensive description of Dell Enterprise acoustical design and metrics
is available in the white paper “Dell Enterprise Acoustics.”
Lowest acoustical output that PowerEdge VRTX attains (for example, a low-feature configuration in Table 1.
idle mode), metrics used to describe it, and corresponding configuration and utilization.
Sound power level Sound pressure level Sound quality
LwA-UL, bels, re: 1 pW LpA, dBA, re: 20 µPa Prominent Tones
5.4
36
None present
LwA–UL is the upper limit sound
power levels (LwA) calculated per
section 4.4.1 of ISO 9296 (1988)
and measured in accordance to
ISO 7779 (2010).
LpA is the front bystander position
A-weighted sound pressure level
calculated per section 4.3 of
ISO9296 (1988) and measured in
accordance with ISO7779 (2010).
Prominent tone: Criteria of D.6, D.10,
and D.11 of ECMA-74 12th ed. (2012)
are followed to determine if discrete
tones are prominent. The system is
floor-standing and acoustic
transducer is at front bystander
position, ref ISO7779.
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“Dell Enterprise Acoustics,” Chris E. Peterson, Dell, Inc., 2011.