After changing HDD, CPU fan goes to 3500 rpm on power-on
I just removed my old HDD, just to install an SDD in the HDD slot, and an HDD (1TB SATA on SATA-to-IDE-cart) in my Optical Slot.
Everything seems to have gone smoothly, except... For seemingly no reason, my CPU fan goes to 3500 (CPU at 30-60°C), and my HDD fan to 1300 (HDD at 50°C). I think, at least the CPU fan shouldn't do so...
I already tried resetting the SMC, and reopened it to look if I maybe removed or forgot to reattach a temperature sensor, but both did not bring any solution at all.
Make sure you reconnect the heat sensor on the hdd - that could cause runaway fans. The other possibility is that those drives actually are overheating your machine. You could run a 3rd party fan app. to monitor internal temperature and see if it's really getting that warm in there.
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HDD Fan Control: http://www.hddfancontrol.com
It's designed specifically for this problem.
And, instead of the terrible answer above (which sticks the fans at 1500 regardless how warm the machine is), HDD Fan Control uses the SMART sensors to ramp up the fans when needed.
I really don't understand why this program is never mentioned when someone brings up the fan problem when you change a hard drive in an iMac... but there you go.
Same thing here. All fans are now continually going crazy. Everything is connected fine. I don't get it. An SMC reset doesn't work. PRAM doesn't help. Makes no sense for all the fans to be going nuts. I wonder if it is related to the LCD temp sensor. I wonder if that could be making the fans ALL continually run.
Download SSD FanController, open it and click on Manual. Put the numbers around 1500. That's it. The link is http://exirion.net/ssdfanctrl/. You may configure its preferences as to S.M.A.R.T. You'll find out when you download and install it.
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