If Furmark shows any artefacts or high temps under full stress then there is something wrong with your GPU. Stressing is the only way to confirm stability. In your case you are wondering about temps. This is the only way to determine how much will temps go when GPU and VRAM are under full load. If you pass this you'll won't wonder about any game.
people usually use furmark to test oc stability but if artifact shows even running on reference clock (nvidia or amd original spec not vendor pre-oc setting) most likely there is something wrong with the card. but from what op mention in his first post i think he more interested in what kind of performance can he expect from his card. if so then he needs to look at performance review for the games he intend to play.