First, how much are you willing to spend? If you are in a budget then go with the cheapest GPU. These two brands are basically the same. EVGA, MSI and Gigabyte are the big threes of GPU brands, but if you really want a detailed answer:
- ■ EVGA GTX 970 SC ACX 2.0:
Core Clock 1165 MHz
Boost Clock 1317 MHz
■ MSI GTX 970 Gaming 4GB:
Core Clock 1140 MHz
Boost Clock 1279 MHz
But you wouldn't really see the difference. Get the brand with the better warranty.