Earlier this month NVIDIA launched the GeForce GTX 970 and GTX 980 as their highest-end offerings based on their Maxwell architecture. Since the GTX 750 series debut I have been anxious to see Maxwell succeed Kepler in the high-end space and finally last week I got hands on time with the GTX 980. As long as you are not committed to using pure open-source graphics drivers, the GeForce GTX 980 is the best you can get as a Linux gamer/enthusiast for high performance graphics for ending out 2014.
With the first-generation Maxwell GPUs consisting of the GTX 750 and GTX 750 Ti, NVIDIA made a huge leap forward with the GTX 970/980 to classify them as second-generation Maxwell hardware. These new GPUs introduce features like dynamic super resolution, multi-pixel programming sampling, VR Direct, HDMI 2.0, etc, but in terms of Linux usefulness this may be a completely different story depending on the drivers.
Beyond the GTX 750 series Maxwell, the newest NVIDIA GPUs also have support for H.265 HEVC video encoding support but as of the time of writing this support has yet to be officially exposed over VDPAU for use under Linux but will presumably appear in due time. Sadly, there's no VP9 hardware support.
The GeForce GTX 980 GPU is designated as the GM204 as is the GTX 970 and while being still on a TSMC 28nm process, it does offer significant gains over the previous-generation high-end Kepler GPUs. The GTX 980 has 2048 CUDA cores, 128 texture mapping units, and 64 render output units. The base core clock of the GTX 980 is 1126MHz with a 1216MHz Boost core clock. The advertised TDP for the graphics card is 165 Watts, which falls well below the GTX 780 series at 250 Watts or the GTX 680 at 195 Watts. As with the GTX 750, the energy efficiency of the GTX 980 is one of the truly amazing highlights.
The GeForce GTX 970 is also an incredibly impressive GPU but unfortunately as of right now we don't yet have our hands on any GTX 970 sample to comment further on its Linux support and performance. Hopefully in the weeks ahead we'll obtain a GTX 970 model for a proper Linux review.
Under Windows, NVIDIA promotes the GTX 980 as being around 10% faster than the GTX 790 Ti and it's reported to be around 10~20% faster than the AMD Radeon R9 290X on Windows.