Choose any reference card.
Yes I have to go with that.
I have equal numbers of HIS 5850 Ref cards and HIS 5850 TurboV cards. The Ref cards underclock and over clock better. Ref 5850 you can see VRM temps I dont believe that is possible with Non Ref Cards. But the Non Ref are quieter when O/Cd.
I will only use Ref cards from here on. I think that the Non Ref cards are basically cheaper versions of the Ref Card where the various manufacturers are free to try to maximise their profits by using cheaper components. That is despite what all their advertising bluurb says about upgraded this and that.