I have a brand new desktop with a W7100 and Windows 10/64bit (1151). The latest AMD driver is installed (release data Dec 1st). In Photoshop CC 2015 GPU support is not available (greyed out) but in Lightroom.
If I deinstall the AMD driver via Windows device manager and restart, the device manager indicates the use of an older AMD driver (release date August). With this driver GPU support in Photoshop is available. If I install the newest driver again and restart, GPU support is gone.