no you should definitely replace the graphics card. If it's artifacting, that's the GPU saying that something is going wrong, not the PSU.
If the PSU isn't giving the GPU enough power then you'll just notice a major slow down in 3D applications, or if it's very inefficient then in most tasks you'll see a slow down because it's not able to give the CPU enough power. A the card only takes around 100w on idle so the fact that it's artifacting while idling doesn't bode well for your card.
I suggest you get a new PSU because, I think the PSU is the cause for your card to start artifacting. I get the feeling that at some point or another something happened causing the card to become unstable, which leads to the artifacting. You usually see artifacting if you overclock a card too much and it becomes unstable, and you can fix it by lowering the clock speeds. Since the card is artifacting all the time, it means that your card has been damaged permanently, and if you don't replace the PSU next time something happens you run the risk of blowing a part that you can't replace for free like your CPU or Motherboard and that will cause way more issues than you want to deal with.