If its not hashing then the fan shouldn't spin because there is no load and doesn't require it to spin. The RX series basically have a fan-off feature to reduce noise and prolong the life of the fans. Basically on idle, they are 90% offline pretty much. So its normal.

Most likely the GPU keeps crashing due to a DAG overflow and that's why it fails to hash at all, nothing he can do except just disable the GPU or buy an 8GB or switch to a different OS.

The older GPUs they always had fans that spun at a min speed of like 20% or so, but the new GPUs they usually don't spin at all on idle.