Unigine Valley scales well, the opensource Quake3-ish games do not with AMD Catalyst. Looks to me like AMD is hitting the CPU bottleneck much faster than nVidia. If true, the upcoming OpenGL driver optimizations to reduce the overhead in AMD Catalyst should be very beneficial. We'll see if we learn something at GDC this week.
No announcement yet.
4K Ultra HD Graphics Card Testing On Ubuntu 14.04 LTS