What's up with Discrete GPUs in Laptops

Level1Techs INBOX.deb
1

Hey Logan or Wendell,

Maybe you guys can answer this question for me: why do laptops with a discrete GPU have both an Intel HD 4xxx GPU and an Nvidia GPU of some variant bundled together. I thought the idea of a having a discrete GPU is not to have the Intel GPU. So why do they have both when anyone playing games or doing any kind of rendering would most likely only need the Nvidia GPU? I've also noticed an Intel GPU bundled with a 760M on an Alienware laptop I was playing around with at a Best Buy the other day. So why does a "gaming" class computer have Intel HD graphics for? I get that the argument is to save battery life by allowing Intel to handle the "basic" needs, but with the way Nvidia is able to automatically under-clock the GPU for power savings, is the Intel GPU necessary for that even? 

I don't know if its just the laptop I have (Asus N550JV) but as you can see from the screen cap below, only the Intel GPU controls display out, resolution, and color. The 750M is only there to serve as a processor. I would rather prefer Nvidia control everything and completely omit Intel altogether. This really bugs me because I have to use Windows utilities when setting up extended displays. 

Also I noticed that the 750M runs off of 900 MHz (1800 effective) DDR3 video memory. Why would anyone put that on a discrete GPU? 

2

That's just how the processors are manufactured, those processors are designed to be implemented into any machine and some machines don't have discrete GPUs. It just makes since to manufacture CPUs with iGPUs rather than create more SKUs with little to no real benefit

3

Also the iGPU can be used and the discrete GPU disabled during tasks the extra power isn't needed to help conserve battery life.

4

Well why would they not have the Intel graphics in them? Think about it the chip is made with the graphics on it, why would they build another chip for laptops where they laser out that part of it, it doesn't make much sense. The chip is also used in laptops that don't have a discrete graphics card, which means it makes sense to have it even in systems with a discrete card.

5

Power savings and heat output is the biggest reason. 

Yes, you could just underclock the discrete GPU but it will still use more power and create way more heat then an iGPU would. 

6

the cpu without the intergrated graphics cost MORE. go figure.