Replace Original HDD with SSD in 2011 21.5 in. iMac

[trancinchino]

Sorry if this topic has been beaten to death, but I haven't yet found a consistent answer across several different forums.

I've read that if you replace the original HDD with an SSD, then there will be a problem with the fans and temperature sensors which ultimately cause fan speed problems.

I've also read that yes, you can indeed replace the original HDD with an SSD without any issues.

Which is it? And if its possible, what types of steps do I need to take to successfully complete the process. Do I simply follow the "replace HDD" guides and use an SSD instead of an HDD?