Y500 heat and question about ultrabay

[Manonassar]

am using Lenovo Y500 
i7-3630QM
RAM 8GB
single GT 650M
while gaming the heat goes up untill 85 then i quit the game to cooldown (GPU HeatP
is 85 safe ? 
which heat i must quit the game ?

i want another GPU with the main one (ultrabay)
i see there is gt650m sli ultrabay it i can use that 
but can i use another sli ultrabay i mean like 750m or 755m ?

[leftrightother]

You can only use the  gt650m sli ultrabay. When you run video cards in sli the have to be the same.