Strange. I got Momentus XT 500GB one with SD23 installed, I did not update it at first, as I saw on Seagate's forum people complaining problems with SD24, and people suggest that if you are fine with current firmware, do not upgrade it, so I did not upgrade it at first.
What I noticed, is that the Load Cycle Count of SMART values does not increase at all, it means the HDD's head never packs by itself, only when mac's sudden motion sensor detects shock and forces it to pack. The result is there is no clicking noise. But this is not good for data integrity as well as power consumption, also, I read the article:
http://xenomorph.net/misc/clicking-hard-drives/
Where a Fujitsu engineer said the load/unload(which generates the clicking noise) is necessary to prevent the head scratch the disk in case of a shock, and normally a HDD can last for more than 600000 load/unload cycles, I also noticed in Seagate's official website, in the specs of this drive, the load/unload is 600000+, see the plus sign at the end, I also checked Hitachi's spec, there is no plus sign
Finally, I upgraded to SD24, then things become normal, the head parks frequently, I'm not sure if I did the right thing...
Lastly, I returned the drive(with $20 restocking fee) as it vibrates much more than previous Hitachi 7K500 drive(I could feel the vibration with XT, but not with the Hitachi one), also, the noise is more noticeable. These two problem does not relate to the firmware update though.
