Every gaming PC needs a good graphics card, because no matter the other components, it's the real workhorse. You can have the fastest CPU, storage, and memory around and still end up with a lame duck if you don't have an appropriate graphics card. It's the beating heart that pumps red-hot pixels onto your monitor.
Nvidia continues to lead in overall value, performance, and efficiency, and the GTX 1070 continues as our pick for the best graphics card. It's not the only card worth considering, however, and depending on your budget, resolution, and other interests the monstrous GTX 1080 Ti or modest GTX 1060 3GB might be a better option.