I based it on this reddit thread and another one which I can't find.
http://www.reddit.com/r/litecoinmining/comments/1rurj5/what_are_your_r9_290_and_290x_settings/

running with 830 and 1500 doesn't crash the computer, but my x session freezes so I can't tell the hash rate. When i remote login via ssh the cgminer process seems to be running. Is there any way to tell the hashrate via ssh?
Am I supposed to run cgminer from within an x session?

These are my first tests with this rig, I never ran it for more than a minute.