hm... dont know if this will work
but you can try going to catalyst control and disable overdrive if it is enabled
just uncheck the box by the overdrive
I had this problem today, same card (2nd day of using it on a dual monitor), but I'd not touched overdrive. However, after reading this I selected 'default' in CCC settings (couldn't see a 'disable overdrive' option) and...
Great tip thanks. My guess is that when I increased the refresh rate from 60 to 75Hz on one of the monitors it must have triggered an overdrive function and didn't reset it when I reverted to 60Hz.