The Gigabyte GV-N770OC-2GD and GV-N780OC-3GD are good video cards. Their performance is in line with other GeForce GTX 770 and 780 cards, and the overclocking potential is fine. A strong side of these cards is how silent they are when idle.
You do software updates to get the most from favourite programs right? Updating a motherboard BIOS can in a timely manner is also critical. The guide to Flashing a Motherboard BIOS spells out the often complicated steps in plain english. PCSTATS Tips