I thought doing 15KHz was the point of a multi sync, also aren't Atari's the same when it comes to monitors anyhow???
The lower two screen modes (the ones with colour) are 15KHz, the high res screenmode (640x400?) the Black and White one is 31KHz.
Well, that's for the native screen modes ala ST. Not sure about the ones with GFX cards like the Falcons etc can use.
