AMD uploaded Catalyst 14.7 RC3, you can download this new test driver over here. The update fixes issue with 4K screens and has performance enhancements for Lichdom and Watch Dogs.
Feature Highlights of the AMD Catalyst™ 14.7? RC3 Driver for Windows:
Includes all improvements found in the AMD Catalyst™ 14.7 RC driver
Display interface enhancements to improve 4k monitor performance and reduce flickering.
Improvements apply to the following products:
- AMD Radeon R9 290 Series
- AMD Radeon R9 270 Series
- AMD Radeon HD 7800 Series?
Even with these improvements, cable quality and other system variables can affect 4k performance. AMD recommends using DisplayPort 1.2 HBR2 certified cables with a length of 2m (~6 ft) or less when driving 4K monitors.
Wildstar: AMD Crossfire profile support
Lichdom: Single GPU and Multi-GPU performance enhancements
Watch Dogs: Smoother gameplay on single GPU and Multi-GPU configurations?