Hi I've installed my Radeon RX580 Sapphire Pulse into my Mac Pro 4,1 >5,1. I'm on High Sierra 10.13.6. I've connected two Dell U1527H monitors via DP out to mini DP in. I have a third Apple Cinema display connected via DVI. The problem: on the Dell monitors there's a strange pixel shift happening on small text as per the attached picture. This happens on any small text whatever the colour. As you'll see, this isn't happening on the Apple display. The pixel shift doesn't happen when I connect one of the Dell displays to my Nvidia GT120. I've tried reseating the card. I've tried disconnecting the third Apple display. I've also toggled 'use LCD font smoothing when available' in system prefs which removes the shift on light text on dark but makes the text look awful. None of these things worked. Of all the reports I've read about the RX580 install I've not seen this issue. Has anyone else? Does anyone have any insight on what may be causing it? Thanks.