I have two Power Color 7950's in crossfire. Monitoring is done via Aida64 through Aquasuite. 
Upon first installing Aida64 updates both gpu diodes normally show  up, yet after a time the second gpu disappears from the Preferences / External applications section, and thus does not get written to WMI. 
  
Sometimes I can fiddle with gpu-z or other apps and get the gpu 2 diode to show up, lately not so much. 
  
Any fix for this?