Configuration thoughts

Hi every one, after reading the configuration guide and having a tight budget I configured the following hardware on my 2009 MacPro. Bought form macvidcards a GTX470 and had it pared with the GT120, added 16GB of RAM and a 512GB M4 crucial SSD along with a decklink SDI i/o card for my BM smart view monitor.
So far so good, the down side is I'm still using V8.2... Anyway, I'm only grading cinemaDNG materials (2K) and with out any notes I get 10FPS for play out. I've tried lowering the playback res, but nothing changes, adding notes playback drops to 5FPS. What should I do? Get rid of the GT120 and replace it with another GTX470? get rid of the 470 and get a faster one? Any thought will be appreciated!
kind regards
John
So far so good, the down side is I'm still using V8.2... Anyway, I'm only grading cinemaDNG materials (2K) and with out any notes I get 10FPS for play out. I've tried lowering the playback res, but nothing changes, adding notes playback drops to 5FPS. What should I do? Get rid of the GT120 and replace it with another GTX470? get rid of the 470 and get a faster one? Any thought will be appreciated!
kind regards
John