Can't use Radeon GPU to render in cycles (R9 270) In the settings I can't choose another device to render other than the CPU. 



According to the blender wiki the GPUs "with a GCN Architecture superior or equal to 2.0 are supported". 



And as I understand my GPU (R9 270) should be supported, according to this table from wikipedia(and has GCN 2.0 and up):


Or am I wrong and my GPU isn't actually supported? :( 

GPU:    R9 270 (latest drivers)

OpenCL version: 22.19

Blender version: 2.79
R9 270 is actually GCN 1.0 architecture and is not supported after Blender 2.78c.

If you look at the wikipedia chart for the Radeon 200 series products, you'll see that the 270 is actually a GCN 1.0 hardware. Which was dropped from Cycles in Blender 2.78c.