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. That's important, because when you're not gaming you really don't want to hear the card. Under load the noise levels are average.
The price is also a strong point of these cards. Gigabyte's GeForce GTX 780 OC costs an average of £ 568, and the 770 an average of £ 328, both very competitive prices.
However, MSI has the same appealing combination of low price and low noise with its TwinForzr cards, click here to compare their cards. MSI has the cheaper 780, but other than that it's basically a draw. Gigabyte is slightly faster in most benchmarks, and also quieter when idle. MSI's cards are more silent under load. In the end, go for the card you can find the best deal for.