I have a V5500 and a V3000, and I must say that i prefer my V3 atm, i can't get the picture on V5 to be as sharp as on V3.
It may just be a matter of fine tunning some screenmode settings, as the guy i got the card from, lempkee, said picture quality was great.
But yes, it requires power from the tower, guess to run those TWO fans on the chips...which in my opinion makes too much noise.
Also, it's so huge that if you have an E-Box + Mediator PCI 1200, it can't be in slot 1 because of its length.