Well I want to buy a GPU because I am going to build a PC and I want to know which one is better, the 7970 or the 770. Also, which card brand is better and which one is more powerful. SAPPHIRE Radeon HD 7970 3GB vs MSI GTX 770 2GB. I know but not 100% that the 3GB in a GPU is for the monitor dimension. Well, I'm buying a monitor IPS 1920 x 1080 5ms.