2011 imac 27" 32GB - final stage of 1TB + 2TB SSD upgrade (replaced HDD & optic drive). Also cleaned out the fans and case. Running 'SSD Fan Control' & 'Macs Fan
Solving iMac fan noise issue after HDD replacement - CrystalIDEA Blog
How-To: Now's the right time to swap your old iMac's hard drive for a fast new SSD - 9to5Mac
New Apple iMac Has a Meltdown If You Replace or Upgrade the Hard Drive - ExtremeTech