Gaming has now hit a snag

To begin with these are the specs to my computer:

1) Intel Core i5-3450 3.1GHz
2) Galaxy GeForce GTX 560 Ti GC 1 GB
3) Corsair Vengeance Blue 8 GB (2X4 GB) RAM sticks
4) Corsair Enthusiast Series TX 750 Watt
5) all of this is encased in a ASUS Essentio CM6830-US-2AA Desktop.

Gaming Wise this computer has been great until recently. But ever since I've started try to play Saints Row the Third and Far Cry 3 its been freezing up and I usually have to do a manual shut down. Before i could run Saints Row in DirectX 9 no problems but Far Cry 3 would freeze up in the first cut screen. Now at first my friend thought it may have been the fact that my driver hasn't been updated. Which was true, but since I've updated my driver my rig is freezing up and resetting even more. Now the update is completely up to date. Can anyone firstly know how to fix the problem, and secondly know how I should improve my rig.