After last week carrying out separate NVIDIA Windows vs. Linux OpenGL benchmarks and similar AMD Radeon Windows 8.1 vs. Ubuntu 14.04 tests, today we are pitting the GeForce and Radeon graphics cards against each other on Ubuntu Linux with the very latest drivers to see how their performance compares now head-on. With this testing we have some Steam games plus are also monitoring the power consumption, performance-per-Watt, and GPU thermal metrics.