I disagree that the GPU can not drive the Retina Display LCD, less Vram would prevent it from only displaying the higher resolutions, assuming that the LVDS display connectors use the same pin out's, what needs to be checked is if the WLED driver chipset is the same, and the 0402 backlight fuse is of a higher amperage rating then a non Retina display model. If your logic made sense, then I would need a special video card to drive a 4k external display, yet they still use a standard HDMI or Dual Link DVI connector as a standard external LCD display.
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