iMac 27" 2011

Hardware Hub Storage
1

So Im looking to upgrade my 2011 iMac i7 16GB 1TB to add an additional SSD. 

  1. Im not even sure if this supports SATA III or SATA II. 
  2. a lot of the suggested hard drives from http://eshop.macsales.com/shop/SSD/OWC/Mercury_6G/ are older and I don't know if there are firmware updates or support anymore.

What should I buy?

2

According to this site it supports SATA III.

However, this page says that upgrading the hard drive isn't recommended due to a whole slew of reasons (including failing the Apple hardware check).

EDIT: The SSDs on OWC actually seem pretty decent. Looks like it's a SandForce controller as well, so it should be fairly common still. You also should really never need to update firmware related to SSDs and hard drives.

3

The problem with swapping out HD's in any iMac is that apple proprietary seagate hard drives have secondary temperature sensors built in that the majority of drives don't have or don't use. I pulled a broken 1TB seagate out of my 2010 iMac and the fans started running at full blast. The only way to fix it was to disable power to the fans during startup and then use a fan controller program once I got into the OS.