AMD has released the new Catalyst 14.7 RC3 drivers, which no longer support Windows 8 - something that AMD hasn't supported since the Catalyst 14.6 Beta driver. AMD recommends that Windows 8 users upgrade to Windows 8.1 for free, so that they can take advantage of the new features found in the Catalyst 14.7 RC3 drivers.
The new Catalyst 14.7 RC3 drivers offer "display interface enhancements to improve 4K monitor performance and reduce flickering" with the Radeon R9 290, R9 270 and HD 7800 Series all benefiting from this. The new drivers also offer some perofrmance improvements at 4K when gaming on Assassin's Creed IV, with up to 93% more performance with CrossFire.
You can download the new Catalyst 14.7 RC3 drivers here.