Hi, I've noticed my mac pro (4,1- 2.66ghz Quad-Core Intel Xeon, 6gb ram, SSD) struggling to play HD video in FCPX when filters or effects have been applied. I wanted to know if upgrading my graphics card will help with this problem? I've never really understood if installing a SECOND NVIDIA GeForce GT 120 would help with this type of problem, or if installing another graphics card would just enable me to plug in more monitors? If this is the case, can anyone recommend a replacement, but compatible graphics card that will help?? Many thanks!