Hi all. Here's my story Removed Hitachi HDD from my iMac 20inch(Early 2009) , installed Seagate Barracuda 1TB. I have heard that I should stick to the same brand but its a bit late for that now. The drive works well. Problem is : Fans run at full speed from the time I turn the computer on and only stops when I shut down my Mac or put it to sleep. I tried resetting PRAM , resetting SMC , downloaded and tried HDD fan control , ran the smc fan control in Terminal with no luck. I tried smc fan control and it doesn't allow me to change the ODD speed(Which shows a minimum value of 5100rpm). My smc fan control values are ODD 5100rpm , HDD 1419 , CPU 3847 I have attached my iStat values here. I have heard of people removing the temp sensor cable to fix the problem. My question is , how do I do that? Which sensor cable should I remove?