Unfortunately, in recent 5.0 rolling releases it is no longer possible to turn off the screensaver with the x-server arguments in /etc/slim.conf. A while back I posted a comment on the subject but didn't receive any reply.
But of course it is still possible to get rid of the screensaver if you are using a full live or core installation (not gtk, justx or base):
1) create an "autostart" sub-directory in your user directory...
mkdir -p /home/???/.config/autostart
2) create/edit file "xset-screensaver.desktop" in autostart...
leafpad /home/???/.config/autostart/xset-screensaver.desktop
... so, it looks like this:
[Desktop Entry]
Type=Application
Name=xset screensaver timeout
Exec=xset dpms 0 0 0 s 0 0
3) save the file and restart the desktop or reboot your pc
and check if it still bombs out after 10 minutes.