Cannot set iMac 27” 5K Retina 2017 to 1920x1080 res.

Dialabrain, thanks, but why? As far as I know aspect ratio on the 2011 iMac should be the same as the one of the iMac retina 5K 2017, that is 16:9, and this is true even considering the differences in overall screen resolutions between the two (that is, Retina vs normal res). Am I wrong? 😕

In fact, for instance, I cannot set such a resolution in my older 2008 iMac 24”, since it has a screen aspect ratio of 16:10, but instead with 27” iMac models, the aspect ratio should be the same.

Malcom, if I check that option, the Control Panel would simply show same resolutions but using low graphics and text, thus using less graphic resources therefore lower resolutions, so to speak. In any case, 1920x1080 wouldn't appear as well. It' the first thing I tried (it's my first time with a Retina display of sorts). Let me show you:

So far, no good… but I really appreciate the quality of help we Mac users can get in these Apple forums.

Thanks to avery one.

Hmmm, thank you, Dialabrain.

Strangely the Mid 2011 27” iMac have has been set ‘down’ to 1920x1080 since the very beginning, while I was running MacOS X 10.6.8 Snow Leopard (as I am sure you well know, the iMac 27” 2011 can run at a native resolution of 2560x1440 pixels – which is way too detailed for my purposes and liking)…

…so, just like you, I am not sure what to tell you in response. 😊

Anyway, thank you, again, for having taken care of my problem.

Thank you rkaufmann, I well know the sevice, as I've been using Macintosh computers since 1990, but the real question here is… can the above described iMac reach such a screen resolution rather than not? It is paramount that I knew this BEFORE calling Apple Care, if ever…

Thanks.