Alienware 15 R2 + AGA ?

Hello everyone,

I have a Alienware 15 R2 (I7-4720hq + 16Gb Ram + nvidia gtx 980m) and want to use for it with the HTC vive which is not possible due to the Nvidia Optimus problem. Therefore I was wondering if I would help to buy the Alienware graphics amplifier and a gtx 1070 (or 1080). Will that solve the problem ? Is this possible for my type of laptop. What card do you suggest for the best results ?
Thanks in advance, Bart