Two things to try off the top of my head. try a clean install of the drivers. also is there any way to try the card in a different machine?
Which Radeon R9 290X model are you using, is it a reference design version like in the picture below?
Which AMD Catalyst version drivers are you currently using? You can find out by Opening Catalyst Control Center and checking the Information>Software tab on the left hand side.
You can use the Performance> Graphics OverDrive tab of Catalyst Control Center to monitor GPU Temperature and monitor Fan speed.