The computer will be used mainly for gaming. The 780 seems to be better but it has a lower core clock.
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http://www.pccasegear.com/index.php?main_page=product_info&cPath=193_1486&products_id=23808
http://www.pccasegear.com/index.php?main_page=product_info&cPath=193_1483&products_id=27293
http://www.pccasegear.com/index.php?main_page=product_info&cPath=193_1486&products_id=23808