Sorry it seems you were mislead. The Radeon 250 is designed for small PCs or home theater PCs. The 280 is more designed for gaming PCs. A GTX 760 is a mid-range graphics card from 2013 and it's 231% faster than the Radeon R7 250. If you have the 250X, that difference goes down to 120% slower than the GTX 760. I have a GTX 770 and in games like The Witcher 3 or GTA5 it struggles in some areas. In short, your graphics card is your big problem. It can be replaced without replacing the PC although after you do that the CPU will become the big weakness. Complete rebuild is ideal.