Try these links. A bit pricey, but will do the trick.
http://www.ebay.com/itm/CLEVO-P15xSM-P17xSM-VGA-Upgrade-Kit-NVIDIA-GeForce-GTX-870M-6GB-DDR5-MXM-3-0b-/111317945660?pt=PCC_Video_TV_Cards&hash=item19eb110d3c
https://www.youtube.com/watch?v=DxqOvQLGK-0