i was planning on buying and amd fx 8320 but want to know if its okay to use the stock cooler while playing games like watchdogs ,im not gonna overclock it one bit
Unless you have really high ambient temps (30C+), you'll be alright with stock cooler. Consider FX 8350, its a better value if you don't want to OC. And both would loose to i5 4440 on stock, by a margin.
Try it, if it overheats then buy a cooler. It depends on how good the airflow in your case is and the ambient temperature of the room you're in. You can monitor the temperatures using a free program like Speedfan