Question dual channel issue

[quebec_frank88]

i bought 16gb 2x8 stick of ram recently ... manual says i need to put it in the same coolor dim slot but when i do i get the 16gb only 8gb usable ... only way to make it 16g usable is to put it in slot 1 and 2 so i dont get dual channel ... does it really make much of a different for gaming

 

[rgd1101]

full system spec?