I've read literally hundreds of posts around the internet from people with cards from all manufacturers with the same issues.
This is BULLSHIT AMD.
I've gone out and spent $600 on new matching monitors, plug them in, flickering and BS all over the second monitor. Google it, common as anything.
I have never overclocked my card/s and now have the Overdrive disabled (From it's default of enabled?!) completely. This makes no difference.
From the info I can gather online the issue is due to the cards changing from 3d to 2d clocks all the time or some BS that I should NOT HAVE TO KNOW ABOUT. The "solution" is I need to either literally "play" around with the profiles and BS until I get it right or go trying to flash the BIOS of the device with another vendors BIOS and potentially kill my hardware...
As someone who has stuck with AMD since my first PC with it's K6-2 I'm beyond infruiratied that this could even happen, let alone that even with the latest drives it's still not fixed. I goto my vendors support site (Gigabyte) and the support/warranty is "return to place of puchase (NOT OUR PROBLEM HAHAHA)".
If I don't have a exact fix for this in 24 hours I won't touch an AMD product again and I'll be sure to advise every person who asks of the way you "support" your products.