Comment by wlesieutre

Unfortunately not anymore. https://support.apple.com/en-us/HT204592#requirements

> iMac (Retina 5K, 27-inch, Late 2014) and later iMac models can't be used as Target Display Mode displays.

Or does that description apply only to 5K iMacs and not to ther other models? The "and later iMac models" statement reads as very broad to me.