Hi guys and gals, I wrote the popular tutorial sometime ago regarding upgrading 2009 iMacs with SSD drives, in the tutorial I theorised that upgrading the primary drive was possible if another drive from the same family was used (To enable proper thermal control i.e No silly fan speeds!). Fast forward to today and I have decided to modify a 2011 21.5 iMac, I have installed a 3.5" Seagate Barracuda 2TB drive in place of the stock 500GB model. Now here is the exciting part..... I have no accelerated hard drive fan, I have no system issues, I can read S.M.A.R.T info from the drive and have comfortable temperature readings. Now the confusing part.... I have also installed a SSD along with the optical drive and upgraded primary drive (Now 2TB). My question to anyone with knowledge on the matter is this: Is it possible that the firmware on the Seagate Barracuda 2TB 5600RPM Drive is compatible with the Temperature detection utilised on the 2011 iMac SATA cable? Could this be a fluke? Please request screenshots for more info to further research this for the good of the community in 3 years time(ish) (Some users may wish to replace failed drives/upgrade out of warranty) If we can establish what is happening here be it firmware or connector on the drive we can provide a viable upgrade/replacement path for every user. Thanks for your time.