I've got a ARCTIC Freezer 7 Pro Rev 2 and after it was through the luggage of an Australia > Europe flight, sometimes it refuses to work and stops spinning. I'm not able to figure out why. How can I diagnose the problem?
It's damaged and needs to be replaced. It possibly got squashed, or lubrication did not like the low pressure of the cargo hold or whatever and now the fan has a higher resistance meaning it needs more current to start.
That said, it's conceivable (but unlikely) your new environment is simply cooler and the fan does not need to run as much. Get some CPU monitoring software and monitor the CPU temp. Also get something (like prime95) to stress test CPU and see if the fan kicks in to FL gear - good - or if it starts to reduce CPU speed - bad, it's throttling because it's to hot.
If it only stops sometimes and your environment is cool, then the heat-sink on such a large cooler might be doing an adequate job of cooling the CPU by itself.
Monitor the CPU temperature to find out.
In fact you mention moving from Australia (I assume hot) to Europe which makes me even more suspicious that this could be the cause.