I bought a Seagate Barracuda XT 2TB (ST32000641AS) to replace a the 500GB Seagate hard drive that came with the machine (ST3500418AS). Same brand, same connectors, though the hard drive fan now spins up to over 5000rpm after a few minutes. Tried SMC reset, but no change. I am now using smcfancontrol.app (2.2.2) to get the hard drive down to a half way acceptable 2500rpm. The temperature value of the new hard drive does show up in the istat pro widget (29c), however, in the slightly older smsfancontrol.app (2.2.2) it reports the temperature as zero. Anyone who have had experience with this? Did some googling, and it seems to me that Apple adds special firmware to these drives.