The 17-Inch and 20-Inch iMac models from the "White" series iMac Core 2 Duo have the same housing and stand as the original Intel powered iMac Core Duo series, and these models are VESA non-compliant as well. The new 20-Inch mac pro i7 4k "Aluminum" iMac Core 2 Duo models also are not VESA compliant.

The confusion is because Apple at one time did provide an optional VESA adapter kit with similar iMac models. The earlier iMac G5 models that could be made VESA compliant with adapter kits by Apple were: Two models with 20-inch displays -- the iMac G5/1.8 20-Inch and G5/2.0 20-Inch, and three models with 17-inch displays -- the iMac G5/1.6 17-Inch, G5/1.8 17-Inch, and G5/2.0 17-Inch.

With regards to iMac models offered after these pre-iSight models, only the 24" iMac computers have had VESA adapter kits available from Apple. The 17" and 20" iMacs were left having no VESA bracket kit option and more importantly, no easy method for removing the stand. Because of this, and the fact that most people who purchased the 17" and 20" iMac as a "portable" computer, it made sense to develop a VESA adapter kit for the iMac that wouldn't require the stand to be removed or any modification to be made to the iMac computer. This VESA adapter kit provides the best of both worlds to the end user as it allows them the ability to attach their iMac to a VESA mounting system and mount their iMac the way they would like to i.e., above a work surface, wall, kitchen cabinet, etc. And, when they decide to temporarily move their iMac to a different location, or take it with them when they travel, the iMac is ready to go with a few turns of the bolt assembly.