I'd go with the 5 to be safe, but do have a look at the VF700's. Much nicer build quality and cools the gpu a tad better (in my case) than AC's offering, but depending on your setup and what you want out of it, the AC could be a better choice. I had both....went with the AC soley on the fact that it exhausts the warm gpu air which in my case was a large benefit. With a oc'ing utility (I use RivaTuner) you can control the AC fan (Zalman too) like SpeedFan. Njoy!