Having occasional artifacts and finally a blue screen caused by GPU's (two R9290X-DC2OC in X-fire) I decided to unlimit available power as an experiment. Windows 7 power scheme set at "performance" and disabling ULPS in the registry helped the problem. It didn't cure the artifacts it but helped a lot and no blue screens! I believe my probs are driver related since each driver release changes the frequency and intensity levels. Using the 14.3 betas for now.