ok but is there any reason why the frame rates would just drop very low all of a sudden.
For example when playing Counterstrike Global Offensive with the surface book lid closed and connected to external monitor. In the beginning I will get for example over 100 fps then after a few minutes it will drop to like 30-40 fps. It's as if it somehow switched to the intel graphics.
It's either that or it's due to excessive heat I'm not too sure.
Playing with the lid open however gives no issues.
I know it's an old and dead thread but I'd like to give my contribution.
The problem is the closed lid.
Being the exhaust for the graphics card on the base, keeping it closed it would prevent heat to be exhausted and also create an hot environment for the rest of the machine (it affects the tablet portion too).
It's not very healthy in the long run for the batteries as well, due to excessive heat transmitted by the chassis.
What you experienced in terms of frame dropping is the thermal throttling kicking in to preserve the electronics.
I've done extended tests monitoring temperatures, clocks and a specific parameter which indicates specifically the thermal throttling.
If there isn't enough dissipation it kicks in and lower the frequencies.
That's why you lost a lot of frames!
The demonstration of this is that you played with the lid open and you had no issues.