I am considering the 860 as pvr option instead of keeping my 24 hour a day noisy topup tv unit.
When in standby, does the fan and or HDD shut down. I know when recording it will be active but I'm hoping it's silent when not actually being used.

It shuts down during standby, and only works from time to time whilst the box is on (when it gets too hot presumably). There are lots of complaints on here that the fan is noisy, but in my experience, its not a problem.