I would go with the OCZ or Hiper. I know OCZ has some good stuff and although Hiper had some issues with their first line of power supplies (this was a couple years back), the second generation they had fixed all of that and was rated very highly (not sure which generation those are, I've not paid much attention since they do not sell in the US to anywhere I've seen). Also if it is SLI Certified it has to have enough power for some level of SLI according to nVidia's testing.