Please explain exactly how a 2nd GPU reduces rendering/analyzing time. I'm very curious about what u meant when u stated this.
On my machine. If a single 7950 require 1min to finish the job (e.g. optical flow analysis / rendering), then 2x 7950 only need something like 35s to finish the same job.
Anyway, I am a FCPX user, and it seems that you already uninstalled FCPX long time ago.