Acoustic Noise and Fan Speed

Acoustic Noise

The following table includes acoustic specifications of the Extreme 7720 Series switches.

Switch Model Bystander Sound Pressure (at 27°C) Declared Sound Power (at 27°C)

7720-32C (AC/DC PSU with front-to-back airflow)

45 dB(A)

6.9 bels

7720-32C (AC/DC PSU with back-to-front airflow)

52 dB(A)

7.3 bels

Fan Tray and Speed Variation

Fan speeds are adjusted based on calculations of the temperatures on all sensors. Due to one fan being located behind the other, air pushed from one fan can cause the other fan in the module to run at a higher speed. One fan can run at medium speed while the other can spin at high speed if one is close to the temperature boundary.

Table 1. Fan Tray and Speed Variation
Description Operation Status Operation Speed Airflow Direction
Tray 1 Fan 1 up high speed Unknown*
Tray 1 Fan 2 up medium speed Unknown*
Tray 2 Fan 1 up high speed Unknown*
Tray 2 Fan 2 up medium speed Unknown*
Tray 3 Fan 1 up high speed Unknown*
Tray 3 Fan 2 up medium speed Unknown*
Tray 4 Fan 1 up high speed Unknown*
Tray 4 Fan 2 up medium speed Unknown*
Tray 5 Fan 1 up high speed Unknown*
Tray 5 Fan 2 up medium speed Unknown*
Tray 6 Fan 1 up high speed Unknown*
Tray 6 Fan 2 up medium speed Unknown*

* - The color of the tab on the fan tray indicates the airflow direction: