Help needed in deciding update for alienware 17x r4

My bro bought an alienware m17x 2-3 yrs back with gtx 660m. Now after seeing the performance gap between 970m and 660m he wants to upgrade to 970m. My questions are:
1)Will his 3d 120hz display work after upgrade?
2)Is there any need to change the heatsink or fan?
3)Any other prerequisites i should know about?(i know we need UEFI boot and only win 8 and 8.1 works as of now)
@Mr. Fox pls help
We...

Help needed in deciding update for alienware 17x r4

Help needed in deciding update for alienware 17x r4