so this was with water only? nice!!!
so when are you going for the mach2 units?
4870s are burning up around 170W at stock already iirc... so those mach2 units will be quite busy removing all the heat, especially when oced!
but im curious how well the rv770 responds to low temps, maybe its mostly heat limited and doesnt need that much extra vgpu... but im affraid it wants volts... lots of volts

and then the gt units are too weak and water might get you better results at high vgpu than mach2 units LOL