I currently have a 990FXA-ud3 rev 4 with an AMD fx-8120, CORSAIR Vengeance 16GB ram, Nvidia Geforce GTX 750 video card.  When I start my system up, it runs great.  But over a period of time, during the day, the system starts to freeze every so often.  What could be causing the problem?  I have the latest drivers for the motherboard and video card. 
alucke