The fan's controlled via a pulse width modulator on the Broadcom SoC. The humax varies the 'On Interval' to change the speed. Fan speed is directly related to HDD temperature but the Humax software only reads the temperature (and varies the fan if necessary) every two minutes. Observed levels with version 1.02.32 are:
When the temperature rises to 55 degrees, on-interval is set to 176
when it falls to 54, on-interval becomes 162
when it falls to 51, on-interval becomes 138
when it falls to 49, on-interval becomes 0 (fan turns off again).
I've also seen it set the on-interval to 200 once and I've tried 255 myself which does run the fan even faster. Maintenance mode in the new CFW 2.19 runs it at 176 which is a little noisy but should stop the HDD from heating up.
I'm building a new package called fan which will allow people to specify a minimum fan level as it has been requested in the past. It's possible that running it permanently at 138 or even lower would stop the drive ever heating up to 55. I prefer it to be silent for the first hour or two but I'm sure some other people wouldn't even notice the low fan speed all of the time but don't like it bursting into life at maximum speed.
My box goes through a fan cycle about once per hour:
Note: The first few posts following this one were originally in the CFW 2.19 thread so were written before this package was announced.
When the temperature rises to 55 degrees, on-interval is set to 176
when it falls to 54, on-interval becomes 162
when it falls to 51, on-interval becomes 138
when it falls to 49, on-interval becomes 0 (fan turns off again).
I've also seen it set the on-interval to 200 once and I've tried 255 myself which does run the fan even faster. Maintenance mode in the new CFW 2.19 runs it at 176 which is a little noisy but should stop the HDD from heating up.
I'm building a new package called fan which will allow people to specify a minimum fan level as it has been requested in the past. It's possible that running it permanently at 138 or even lower would stop the drive ever heating up to 55. I prefer it to be silent for the first hour or two but I'm sure some other people wouldn't even notice the low fan speed all of the time but don't like it bursting into life at maximum speed.
My box goes through a fan cycle about once per hour:
Code:
Thu Sep 12 09:12:03 2013 Fan level: 0 -> 176 (0 -> b0)
Thu Sep 12 09:14:03 2013 Fan level: 176 -> 162 (b0 -> a2)
Thu Sep 12 09:20:03 2013 Fan level: 162 -> 138 (a2 -> 8a)
Thu Sep 12 09:30:03 2013 Fan level: 138 -> 0 (8a -> 0)
Thu Sep 12 10:06:03 2013 Fan level: 0 -> 176 (0 -> b0)
Thu Sep 12 10:08:03 2013 Fan level: 176 -> 162 (b0 -> a2)
Thu Sep 12 10:16:03 2013 Fan level: 162 -> 138 (a2 -> 8a)
Thu Sep 12 10:24:03 2013 Fan level: 138 -> 0 (8a -> 0)
Thu Sep 12 11:00:03 2013 Fan level: 0 -> 176 (0 -> b0)
Thu Sep 12 11:04:03 2013 Fan level: 176 -> 162 (b0 -> a2)
Thu Sep 12 11:08:03 2013 Fan level: 162 -> 138 (a2 -> 8a)
Thu Sep 12 11:18:03 2013 Fan level: 138 -> 0 (8a -> 0)
Note: The first few posts following this one were originally in the CFW 2.19 thread so were written before this package was announced.