Hello, I bought a PC from my friend, it's 1 year old, it has GTX 960 4gb, I5-6400, 8gb ram, i watched some videos on youtube, the pc was good it ran gta v on ultra 70fps, but now, when i have it, it runs gta v very poorly, on low it runs on 40-50fps, does someone know where could be the problem? I tried reinstalling windows multiple times, but it didn't work.