Why would NVIDIA Optimus activate only for Laptops and disable for PCs

For those who don't know Optimus is some sort of a technology NVIDIA developed in order for laptops to have the ability to switch between multiple GPUs integrated when needed .

They often claim that this approach is to save power and is not needed for PCs really as those do not run on batteries to need to save power (wondering about all people now shifting to led lights home just to save on bills) .

It is controversial however , it is known that there is a performance gain noticed on laptops with such setups as then Intel manage to lift the load of all desktop 2D/3D overlays and memory consumption (Yes the load persist even if in background) leaving the NVIDIA GPU and its memory all dedicated to 3D rendering .

Now what dazzles me is that you get same drivers for laptops and PCs from both Intel and NVIDIA and yet however those drivers manage to somehow detect weather the setup is a laptop or a PC in order to enable or disable Optimus technology .

So I'm just wondering how exactly the driver is able to tell if the setup in hand is a laptop or a PC for one thing , and weather there had been any trick or mean or a 3rd party tool to fool the technology into working on PCs and that's another .

P.S I did not tackle the issue from AMD perspective but i am sure they have similar technology to Optimus and approach to PCs handling .

Faith said:

I don't know the technical reasoning so I'm going on an assumption, but if it's a mobile chip then it detects a laptop? The driver package contains everything, for the most part, so it will grab whatever it needs from the ID. They mostly use "M" or "MX" in their chipsets there.

good guess aaaand "darn" , now the proper fix would be de-compiling and wadding through zillions of driver dlls trying to investigate which ones query chip / hardware ids and do what with which and patch the appropriate ones ... guess the other option is to create awareness of such a trend so we can make some marsh forcing NVIDIA and AMD to drop such checks which sounds more convenient