I use the XB EVO for 2 780s, so 2 7970s should be fine. As far as top mesh or window panel, that depends on what you can find at the retailers. Cooler Master makes it both ways, but some retailers only carry one or the other. The window panel prevents a top fan, but your NH-D14 wouldn't fit with a top fan anyway. Personally, I don't like the Corsair Air 540, because the external 5.25inch drive bays are oriented so they'd work best with the windowed panel as the top, but the feet shown in the images make the windowed panel work best as the left side.