my gpu can t drive my screen

[Alienware Gamer ALX]

I found that these notebook s gpu can t drive my 5k external screen: is it correct ?

- gt 750m (on alienware 14 - 2014)
- gtx 980m (on alienware 15 - 2015)

 

[SuB]

Yes, it's correct
http://bfy.tw/I5A4
http://bfy.tw/I5A8
Neither will push 5120 × 2880

 

[Alienware Gamer ALX]

Yes, it's correct
http://bfy.tw/I5A4
http://bfy.tw/I5A8
Neither will push 5120 × 2880

argh

thank you