I Have just upgraded to 5.14 from 5.8 and now the main fan is running a full bore and is very noisy, ( it is driving us around the bend ), It was fine under 5.8 only coming on when needed.
CPU’s are only running a 2%
can you create supout rif file and send it to support@mikrotik.com?
see this thread also:
http://forum.mikrotik.com/t/rb1100ahx2-cpu-50c-fan-not-working/54129/5