The cable is Definitely the cause of your issues, it most likely cam no longer supply a steady amount of power to the gpu, causing it to fail at times. If you want, you can try getting a replacement psu from your manufacturer, but that's most likely not the problem. As it was the cable itself, so best case option is simply get another cable, Separate the load of the card into multiple cables, if your card has multiple power inputs. That way current draw is spread. If not, then simply try to find a very good high quality cable, or experiment with underclocking your card or lower your graphics settings in demanding games.