This guide also includes steps to upgrade your iMac's hard drive with a SSD.

Upgrade your hard drive for an increase in storage space. IMac Intel 21.5' EMC 2428 Hard Drive Replacement Replace the hard drive in your iMac Intel 21.5' EMC 2428. It runs at startup and continually to always control the fan correctly, prevent the loud fan noise and protect the drive from overheating.IMac Intel 21.5' EMC 2428 Hard DriveReplacement HDD Fan Control works to fix this issue by reading the drives internal temperature using the S.M.A.R.T protocol and set the fans actual speed to a value good to protect the drive. These programs will not work for this particular issue as they often only control the base speed, and if they do control the fans actual speed they rely on the temperature reported by the sensor which is now incorrect.

Shorting the temperature sensor cable (Not a possibility on 2011 iMacs) this tricks the iMac into thinking the drives temperature is very low, hence slow fan speed.īoth these fixes are less then perfect and leave the drive in a dangerous situation with no protection from overheating.Īnother option people try is other Fan Control software.

Using smcFanControl and the terminal to set a MAX speed for the fan and writing scripts to start this after every sleep/restart.

Fixes people have used in the past included: Resetting the SMC (System Management Controller) will have a temporary effect, but again the fan will speed up. If you replace your drive, your iMac will initially seem fine, but soon the fan will begin to speed up to full speed.

When the iMac does not receive a good signal from the hard drive it puts the fan at full speed to protect the drive. Replacement drives do not contain the firmware to deliver temperature data on the temperature sensor cable. This is due to Apple replacing the external Hard Drive temperature sensor with a proprietary firmware and using the drives internal sensor. Since the late 2009 iMacs came out, replacing the hard drive has caused the internal Hard Drive Fan to start running at around 6000RPM.

Mid 2011 imac hard drive replacement