Originally, I got a mid-2010 Macbook Pro with a Apple 128 GB SSD. However, I needed a lot more storage space than that for media files, so I installed a second HDD (WDC 500 GB 7200 rpm, here is the complete product info) by replacing my optical drive using a combination of the following instructions (iFixit and lifehacker). Everything worked out fine, and it's working great now. I have my original Apple SSD (which is actually made by Toshiba) in the original HD SATA slot, and my HDD is in the second SATA slot where the optical drive used to be. However, I have a slight problem with the laptop's fan. It now runs at an audible level, while before my laptop was completely silent unless the graphics CPU was running. I'm pretty sure it doesn't have much to do with temperature, because if I eject the internal HDD using this Terminal script the fan immediately turns off. I am sure that the temperature doesn't go down the moment I run this script, so maybe it's a built-in OS mechanism to turn the fan on when that SATA slot was being used (ostensibly because a spinning optical drive would make some heat). Is there any way to turn this off? I'm pretty sure it wouldn't make my computer hotter on average than it was before I replaced the optical drive, and it would make the macbook a lot quieter, which is what I am looking for. To clarify, I am just looking to stop my laptop's fan from running unnecessarily (according to my postulation) when the second HD is mounted.