Dell PowerEdge R720 Technical Guide - Page 37

 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 Systems Owner's Manual on Support.Dell.com/Manuals and "Advanced Thermal 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 32. 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). 37 PowerEdge R720 and R720xd Technical Guide