CS:GO & TF2 Extensively Tested On The Newest Open-Source Radeon Linux Driver
The Radeon R9 290 was burning the most power...
But when calculating the power efficiency, the Radeon R9 290 was well out in front as being the most efficient Radeon GPU tested on Linux 3.18 + Mesa 10.4-devel + LLVM 3.6. All the other GCN GPUs were noticeably behind the rest.