Just assembled the Eon today. Noticed the thermal pads are about 1.0mm thickness. With the RPi installed, the CPU wasn’t even touching the pad on the heatsink. That’ll lead to increased CPU temps and more fan noise, which seems like what a lot of people here complain about. I switched the pads out with 2.0mm thermal grizzly minus 8’s. CPU runs around upper 30’s while streaming movies. Fan never turns on. Silent NAS. Check you pads.
I had the same problem when I purchased the EON last year.
At the time I disassembled everything again and placed 2 thermal pads one above the other of 1mm (total 2mm) to fill the space in the CPU and RAM, and the passive heatsink.(box)
In my case I have 4x 2.5’ SSD inside.
Using 4 spacers of 20mm I was able to lower the fan from the top. The airflow output is maintained, but the noise is substantially reduced.
For those using a 3.5’ HDD, this change cannot be made.
After this change, it is very rare for the fan to work as the temperature is between 30 and 42ºC, depending on the ambient temperature, and when it works the noise is not so aggressive.