If you are running eyefinity...since you have to one monitor plugged into a Displayport you may have issues with banding (VSYNC not working) on the monitors that run on just the DVI ports. Something to do with clocksync or some such nonsense.

There is no current fix, the only way to reduce the problem is to get another miniDP-DVI adapter. One monitor will always suffer from this unless one gets a card with 3 miniDP (6990 lolerz).

If by 'banding' you are referring to black horizontal bands travelling up and down the screen vertically, then I have a similar issue with my 5850.

This happens ONLY when I have two or more monitors enabled and have Overdrive enabled as well.

Very annoying, so much so that I can't OC my card at all. Every two or three driver releases AMD fixes the issue then in the next release they break it again. It's a known issue and AMD have not so much as made a comment on it since the 5xxx series has been launched.

When I had the 5870 it was the far left monitor that was hooked up to the DP, and I didn't notice much banding. Somehow when I went to the 6970 the middle and right monitors went batshiat insane with banding. The only way to fix it at this time is to put as many monitors as possible on DP.