If you bought a GTX670 Superclock with the batch product number 02G-P3-2672-KR, you might want to stress out your card for a while and see if anything happens. It might be something, it might be nothing at all discernable to your eye. You might not even know you had a problem and you could go for years without knowing it was there until one day it smacks you in the face with a spade. Maybe you're losing a few frames and your settings are at stock or the fan is too loud. At this point, if you're desperate, you really could make up anything you want until you hit on the right fault.