Not sure but I have the same iMac stats you say, mines 27 inch and 1 tb hard dish (fusion) but after so many video issues on older imacs (yes i know its part of the motherboard now) I use TGpro to keep my fan speed adjusted. That way I always have themps I can see easily and can see if there ever is a problem, I also set them to turn on before the apple set points as solder is lead free and flexing of boards from heat crack the joint, which is what causes G5 tower failures and imac video card failures.