they are both pretty cheap and btw the 660 comes with free watch dogs
http://www.newegg.com/Product/Productcompare.aspx?Submit=ENE&N=100007709%204017&IsNodeId=1&bop=And&CompareItemList=48%7C14%2D127%2D761%5E14%2D127%2D761%2D02%23%2C14%2D150%2D605%5E14%2D150%2D605%2DTS%2C14%2D130%2D826%5E14%2D130%2D826%2DTS&percm=14%2D127%2D761%3A%24%24%24%24%24%24%24%3B14%2D150%2D605%3A%24%24%24%24%24%24%24%3B14%2D130%2D826%3A%24%24%24%24%24%24%24
http://www.newegg.com/Product/Productcompare.aspx?Submit=ENE&N=100007709%204017&IsNodeId=1&bop=And&CompareItemList=48%7C14%2D127%2D761%5E14%2D127%2D761%2D02%23%2C14%2D150%2D605%5E14%2D150%2D605%2DTS%2C14%2D130%2D826%5E14%2D130%2D826%2DTS&percm=14%2D127%2D761%3A%24%24%24%24%24%24%24%3B14%2D150%2D605%3A%24%24%24%24%24%24%24%3B14%2D130%2D826%3A%24%24%24%24%24%24%24