I just found a thread over at overclock.net from a guy who seems to have the same problem as you, might be a few suggestions in there that u can try?
http://www.overclock.net/nvidia/853874-same-damn-problem-7.html
	
		
			
		
		
	
				
			http://www.overclock.net/nvidia/853874-same-damn-problem-7.html
	
 
	