It's not a good idea to render a scean with laptop , i mean a scene which requires days of render. Once i was put a scean on a laptop and render it for a few days but the laptop "burn out". This is coused by the laptop cooling system you can see that the cooling system on the laptop is more simplifyed than the desktop , this is equal to lower quality of cooling ( in general there are exceptions of course). What i mean by that is becareful what you are doing . I have desktop PC now and no problem with long renders ... i'm thinking of buying laptop only for modeling .