do i need to hook 2cables to my 4k monitor and xfire

[Always_Winter]

this is the monitor i have
LG 27UD68-P 27" FreeSync IPS LED Monitor 4K UHD
https://www.newegg.com/Product/Product.aspx?Item=N82E16824025467

also have 2x rx480 gpu

 

[Bacon1]

No only the main / primary card hooks into the monitor