4.3 Thermal Management
The m108 contains a large amount of circuitry in to a very compact 1U chassis. Under normal operating
conditions the m108 will dissipate 20-25W of power depending on user settings. To protect the m108
from excessively high internal temperatures, and to ensure long term reliability, it is equipped with a
40mm variable speed fan. Whether or not this fan turns on is dependent on several variables. These are:
ambient temperature, whether there is air movement around the m108, and if the m108 is mounted in
contact with other heat generating equipment.
The variable speed fan to comes on to cool the internal circuits if the main circuit board temperature
rises above 45ºC (113ºF). The fan has four speed ranges which are triggered by the following pcb tem-
perature points:
1. 45ºC (113ºF)
2. 49ºC (120ºF)
3. 52ºC (125ºF)
4. 55ºC (131ºF)
If the m108 is mounted without space above and below and it is adjacent to heat generating devices
then the internal temperature can rise above 45ºC and the fan will come on.
If the m108 is being used in an area where fan noise is undesirable it is recommended that the m108 be
mounted such that is has space below and above the chassis and where the ambient temperature does
not exceed 30ºC (86ºF). If multiple m108s are to be mounted in a rack enclosure it is best if there be a
space between each unit.
m108 Owner's Manual
page 8
