Sorry, I was in a big hurry and could not write the reasons.
But, it was fortunately covered already.
I think, you should start planing about having a big overhaul.
At least, I ditched my Q6600+HD6850+6GB DDR2 1000 system last year.
My Q6600 rig was already running daily on 3GHz.
I tried Shadow of Mordor on it, after seeing the result I decided that it is time to upgrade.
My Q6600 has been loyal for 8 good long years but I simply needed a more powerful system.