The imac fans will run at full speed if you replace the hdd without the temperature sensor and or proper connector.
Imac 2011 ssd temperature sensor.
Hard drive temperature sensor cable for imac 27 a1419 a1312 593 1029 a.
The ssd connects to a separate sata connector on the motherboard thus leaving the hdd data and power connectors unpopulated.
No fan noise at all so far.
This hack fix bypasses the hdd temperature sensor in order to fool imac into thinking that hard drive is working at normal temperature.
The only imac hdd upgrade option on the market certified to pass the apple hardware test.
Owc 1tb ssd upgrade bundle for 2011 imacs owc mercury electra 1 0tb 6g ssd adaptadrive 2 5 to 3 5 drive converter bracket in line digital thermal sensor cable installation tools owckitim11he1tb.
The imac hard drive has an integrated temperature sensor.
Owc ssd upgrade kit for 2011 21 5 inch imacs owc mercury electra 120gb 6g ssd 18 sata iii 6gbps data cable installation tools and imac screen adhesive tape set.
Owc in line digital thermal sensor for imac 2011 hard drive upgrade required for any drive installed into the main drive bay.
Only 3 left in stock order soon.
I ve booted from an el capitan installer flash drive formatted the ssd and am installing el cap as i write this.
As a build to order option one could order an imac with only an ssd and no mechanical hard drive.
Eliminate fan noise and maintain correct system fan control when upgrading your 2011 imac.