I have recently bought a second R9 270 and enabled crossfire. Crossfire works really well and it doubled my fps in game. After a few weeks I realized that the hdmi sound does not work at all (headphones work fine). Now when I went to look up my sound output it told me that it is enabled and it is working. When I klicked test it even showed that green meter at the right, but there was no sound. I have no idea what this could be!