NVIDIA GeForce GT 640M Imac. Qual a ultima versao do Photoshop compativel

@ChrisAll The only version you can download is Photoshop 22.2. It really has nothing to do with your GPU - it has to do with your OS. 2012 Mac Minis can only go to Mac OS Catalina - meaning current Photoshop and 2023 will not run on it.

What model 2012 iMac?

Since it seems your 2012 iMac most likely only has 512 mb of Video ram, Photoshop 2020 seems to be the newest version that has the requirement for a minimum of 512 mb VRam (video ram), but that also depends on what operating system your iMac is running, how much Memory (ram) and whether you have a spinning hard drive or ssd.

https://helpx.adobe.com/photoshop/system-requirements/earlier-versions.html

None of the Photoshop versions that should fully work on your Mac are still offered for download from Adobe, so that's another issue you need to consider.