even for me it wont use my gpus to their full potential, roaming around with a tone of people on ultra with my textures over ultra it will dip into the 45 range . when I do like a dungeon finder i average 100 fps and my cards are actually being used.
If i remember correctly wow only uses two cpu cores?
The fps you have reported getting and your hardware match up. It isn't a great card, but you are getting about the fps that you should be. If you notice stuttering, then reduce video quality until it plays smooth enough for your liking
After doing a quick search, your processor should not bottleneck a 660. WoW does rely partially on cpu power (ever so slightly more than some games) But a 660ti should not be able to do 60fps on ultra consistantly (maybein dungeons, but should dip lower than that during stressful events like raids or open world roaming