P2014H has jagged scrolling whilst ST2420L is smooth

Hi there,

I've just purchased a second monitor to run on my Dell XPS 8500 with the original Radeon 7700 card in.

I have the ST2420L connected to the digital port and this is in landscape mode.

The P2014H is connected to the DP port and is in portrait mode at 900x1600.

I have the desktop extended across, with the P2014H to the right of my main monitor.

Using firefox on the windows 7 system, the pages when scrolled and viewed in the right p2014H are jagged, a appear broken until scroll stops. Drag the firefox window to the 2420L and the same page scrolls smoothly.

Any ideas?