So as I was pulling apart my laptop earlier yesterday, when I got to the motherboard, I noticed that the heatsink has this rectangular hole over where the cpu/integrated gpu should be. I don't know whether it's the cpu or integrated gpu (intel HD graphics btw) as there's nothing there to discern them but I do know that it's not the dedicated nvidia gpu as that's separate and says 'nvidia' further down. I believe it's the integrated gpu as there's another similar looking metallic rectangle more towards the centre of this particular piece and the cpu is more likely to be in the centre and the gpu is next to it.
This hole baffled me as I don't understand what it's for or how the heatsink works if it's not directly covering the integrated gpu to transfer heat! The rectangular hole perfectly fits over the gpu so it's as if the manufacturers DELIBERATELY went out of their way to make the heatsink have this particular hole for it.
My question is what's it for? Does anybody have any idea? I'm just curious.