D4-320: Fan always on

[olli]

I have an D4-320 which is connected to an ASUS-NUC-15 running Linux via USB-C. If the hard disks are not accessed by the OS, they spin down after approximately 5 minutes. However, the fan stays always on, even if I wait hours, which is somewhat annoying. Is that the expected behavior? Interestingly, the fan turns off immediately if I disconnect the USB cable.

[CursaYang]

The USB ports of mini computers often suffer from weak signal issues. Please use an active HUB for connection.

In addition to connecting through a HUB, you can also try using shorter USB-C cables, such as 30cm or 0.5m, which can also reduce signal attenuation.

[olli]

I am not convinced that a weak signal from USB-Ports is the root cause for the fan not turning off. I did extensive tests with the hard drives and I saw no reconnects or other problems that were observed by other users during transfer of morethan 8 TB of Data. However, I will try to connect the D4-320 to a different compute and see if the problem with the fan depends on the computer. Unfortunately, I don't have an external powered USB hub available right now.

[TMzethar]

D4-320 is equipped with an intelligent temperature-controlled fan. The fan speed adjusts according to the temperature, but it will not stop rotating due to low temperature. When the operating system issues a command to put the HDD into sleep mode, the fan will stop rotating until the HDD is read/written again. When using any SSD, the fan may not stop as SSDs themselves do not require sleep mode, and the SSD's own controller also needs heat dissipation.