Mine was sizzling, right after purchase. Did send back to Futeko and the second Q10 Pro they've send was sizzling just as the previous one. (HA-HA).
Tipp: If the warranty is off, than you may try to swap the fan for a better (and compatible one). Voltage/CFM/RPM and size parameters will all matter. You must choose carefully, so will not be an easy run... (Please, Update in this Thread if you find something useful...) Guess Futeko will gladly inform you towards regarding these parameters...