Thermal management and associated air mover speeds (fan speeds, for example) are most responsible for sounds from computers. Amplitude of sound scales logarithmically with the speed of air movers, so a seemingly small speed adjustment can have surprisingly noticeable impacts. For example, a 10 percent speed change results in a sound pressure level change of approximately 2 dB, while a 20 percent speed change results in a sound pressure level change of approximately 5 dB.
PowerEdge XR4510c and XR4520c were designed to support high performance through extreme temperature ranges. Acoustical experience was not a chief tenet for design. As such, even the quietest configurations are about as loud as that of several people talking softly in a restaurant or the sound of moderate rainfall. Moreover, the quietest configurations have low-frequency prominent tones (hums, for example).
Two components are the primary determiners of the PowerEdge XR4510c and XR4520c acoustical experience. The Dell Boot Optimized Storage System (BOSS), used for system booting, drives thermal requirements for minimum air mover speed and thus determines the quietest states that the XR4510c and XR4520c can attain. In addition, acoustical output varies significantly with the type and operational state of the accelerator. For example, the NVIDIA A2 GPU at full operation results in acoustical output similar to that heard in a data center or that of a vacuum cleaner. Moreover, it contains mid frequency prominent tones (whistles, for example).
Ambient temperature and loading (applied workload) are also key variables that determine acoustical output. As air movers spin faster to remove heat in both scenarios, acoustical output increases. Although the PowerEdge XR4510c and XR4520c are designed for deployments that are not in proximity to human ears, if you need to deploy the systems in quieter settings, consider the following information.
Note: Usually, the system idle air mover speed cannot be reduced without changing the configuration of the system.
- System bootup: During system bootup, air mover speeds might ramp (as high as 50 percent of full speed). This increased speed ensures that cards comply with their thermal limits at an assumed worst-case thermal state before thermal telemetry feedback is established. After bootup, the system ascertains actual thermal conditions through telemetry feedback, and air mover speeds might become reduced.
- Ambient temperature: Air mover speeds increase to bring more airflow to components when ambient environment temperatures rise, and the server becomes louder. Lowering the ambient temperature allows the system to cool components more efficiently than at higher ambient temperatures.
- GPU/FPGA/Accelerator cards: Certain accelerators require significant increases in airflow for cooling and, thus, produce boosts in air mover speed and server loudness. Uninstalling the GPU or reducing its loading allows the air mover to run at a lower speed.
- PCI cards: Replacing third-party PCI cards with similar Dell supported temperature-controlled cards, if available, can reduce server loudness. Dell works diligently with card vendors to validate and develop PCI cards that meet Dell’s exacting standards for thermal performance yet also run the air movers at the lowest possible speed.
- Thermal Design Power (TDP): As the wattage of server components such as CPUs, drives, and so on increases, so do the needs for airflow, air mover speed, and loudness of the server, when the components are under load.
- Storage type: NVMe SSDs consume more power than SAS and SATA drive technologies and so demand more airflow to achieve system cooling targets, higher air mover speeds, and increased server loudness.
- System thermal profile selection in BIOS or iDRAC GUI:
- Default Thermal Profile generally provides a lower air mover speed and, thus, lower acoustical output than the output of other thermal profiles.
- Maximum Performance (Performance Optimized), conversely, results in higher acoustical output.
- Setting target in third-party PCIe card options: Dell provides airflow customization for third-party PCIe adapters installed in PowerEdge platforms. If you want lower targets than those of the automatic cooling response, you can set different linear velocity (linear feet per minute, or LFM) targets by using PCIe Airflow Settings options in the iDRAC GUI.
- Sound Cap: If no GPU is present in the server and the CPU is driving cooling needs, then Sound Cap, a setting in the BIOS, can be enabled or disabled during boot. When enabled, sound cap reduces the acoustical output of the system at the expense of some CPU performance.