I'd get a bigger case and mobo (atx mobo and full or mid tower case) or get a gtx 770 or r9 290. The case and mobo wouldn't increase performance but would make more room for sli if you want to do that and would have better airflow if overheating is a problem. If you want better performance in games the r9 290 would be the best for the performance and price but might overheat in your case if you have poor airflow.