I have a HP chromebnook 2in1 supplied by my school. When ever i use it after 15-20 min it its slows up (less than 1mb internet usage ) I can get any technical info you may need, just ask.
It is 3 months old.
i5 6300hq + 1060. the i5 is a very capable cpu, I have it in my laptop and in school computers, that also run cad, and they seem the same or better has the school's 5th i7 laptops / desktops
i don't believe that you even can replace them, i think they are solderer to the board, but if they are not an 970m might work, don't quote me on that though