Updates HD with Same Manufacture and got the Loud Fan?

The new 2tb HDD could be putting out more heat and thus the sensor picks up the higher temperature reading and tells the HD fans to spin faster. These hard drives are fully compatible with Macs so that is not the problem.

The 2TB one has dual actuators while the 1TB has single and also the 2TB has 64MB Cache while the other has 32MB. These differences in performance and extra moving parts can make a difference in how much heat output the drive has even if they are the same manufacturer and line.

Make sure you put the sensor on the same exact spot. If the fan speeds are faster then I really wouldn't worry about it as long as you keep an eye out on your temperatures. Install iStat Pro widget so you can see if there are temperature differences between the 2 drives: iStat Pro

If the louder fans really do bother you then you can spend about $30.00 more on the 3TB WD Caviar Green WD30EZRSDTL. The Caviar Green line runs cooler and it has less power consumption than the Caviar Black. The 3TB drive has the same specs as your 2TB but it has IntelliPower technology which lowers the RPM when not in use thus reducing temperatures.

http://www.wdc.com/en/products/products....

http://www.newegg.com/Product/Product.as...