What are all differences between the gtx 970 graphics cards, because you have i.e. the TURBO-GTX970-OC-4GD5 and the ASUS GEFORCE® GTX 970 DC Mini small form factor gaming graphics card, but they are both the gtx 970 but the second one costs more than +$100 than the first one, and if there is a differnence, do you notice the difference in games?