Since I just want and entry level gaming PC but can handle competitive level of performance for CS:GO, what is the most powerful GPU that an i3 6100 can handle?
Well if it is only for CS:GO you won't need much of a GPU. But the RX 470 will be a good choice, and maybe the upcoming Gtx 1050. Or maybe an r9 380/380x, which I would not prefer but it's quite cheap since the new GPU's released are taking over the place of it.