Right. Have you checked your gpu utilization to make sure it's actually working?
I use a 42" Plasma 1080p, so its rather obviose to whether its working or not. Without it, i see Alaising, with it on i dont. I also see smoothing of the text. (MHGen)
Honestly of hand i cant recall how much GPU usage went up, but it did.
So yes, its working.