I recently launched a multi-machine Enterprise Portal deployment (10.9.1), and have a couple other machines not yet part of the federation but theoretically available to use as a separate image server.
Both other 'spare' machines are running SQL Server, one of which contains the instance housing an enterprise geodatabase that is a registered data store for our hosting server. This machine was previously running a standalone arcgis server that I have turned off but not yet uninstalled. The other has some SQL databases for other unrelated purposes.
My main question is if there is any reason to not run arcgis image server on the same machine also housing SQL databases or ArcGIS Desktop 10.7.1? Would the different programs conflict at all with each other?