I have 2 x r9 270x cards in a rig with Ubuntu 14.04 (the old fglrx drivers give much higher performance for those older cards and 14.04 is the last version with fglrx).  I can get it running headless but it isn't reporting temperatures - zecminer reports ADL initialization error.  To get it running headless I have to kill the X server first ("service lightdm stop").  After that it mines fine, but i want to see the temps.  I'm also not clear if it's obeying my config -ttli temp limits because of this.