What I noticed however is that the overscan caused by my TV could not directly be compensated by any of the RetroPie software (this was not an issue when I was using this as a media center since Kodi manages overscan easily).
Most of the solutions found on the Internet advise to change the TV settings, but these were not available on my model, so I found the following idea from this post :
/usr/bin/xrandr --output HDMI1 --panning 1280x720 --transform 1.05,0,-35,0,1.07,-24,0,0,1
I had to use the –panning option otherwise I did not manage to get the results to work the way I wanted. You should obviously set the numbers above based on your own setup (you could start with that and tweak them one by one). In case you end up with a wrong setting, look at this.
Once the settings worked for my setup, I embedded this command in a bah script that I added to the Xfce startup list.