Please help me to troubleshoot my laptop's heating problem

Have you enabled VSync in those games or FPS limiter? If not do so. Or you can go to Nvidia Control Panel and in 3d Settings -> Program Settings choose that those gmaes run on Intel integrated graphics.

go to nvidia control panel

It seems that your grafic card just runs at max capacity as soon as you use it.

Try to use the intel one for older games, should be suffiencient. And for games where you need the 950 as mentioned above use v-sync or limit the fps to reduce calculations. But as soon, as you really need the full capacity of th 950 it just gets damm hot. Thats the thing with laptops.

You can screw it open and clean the airpipes/fans maybe those are blocked as well, but only if you know how to not destroy your PC in the Process.

Yea looks like it gets too hot, get some programs like gpu-z and core temp and check your temps when gaming. I had one with 960M and after 2 years I had to replace thermal paste due to overheating so if your temps would be above 80C I would recommend you disassemble it, clean and replace thermal paste.

I tried everything that google searched could offer.

If you already tried everything, what do you want here?

Yeah, 90C is dangerously hot for your CPU actually. I will get her to the shop for a check-up.

Anyway, you can try this to set your default card to your GeForce one, I know I had to do it once before.
https://www.techadvisor.co.uk/how-to/pc-components/how-set-default-graphics-card-3612668/

This is a common problem for ASUS laptops, even ROG's. I work in a PC repair shop and have seen and modded a lot of those. I don't know why, but ASUS made the cooling system draw air from under the keys on the keyboard over the FAN, so if the small holes there get full of dust the fan can't draw enough air in the first place. Second problem is the FAN and radiator assembly itself, the FAN is stuck to the radiator and lined up with some kind of plastic, no gaps at all, so if any dust gets in the fan it has no where to go and eventually plugs up the radiator. The third problem is the GPU heat pipe goes over the CPU, so if the GPU gets hot, the CPU gets hot as well, even worse if the radiator is full of dust and lint :S. There's not much one can do about that, I'd disassemble the laptop, separate the fan and radiator and clean them, clean the holes under the buttons of the keyboard and if the customer wants even drill holes in the bottom of the case, so if the keyboard holes get plugged up the fan has another source of fresh air. The holes on the bottom bring down the temps 10-15 degrees, depending on the configuration (cpu/gpu) of the laptop. So i'd say clean it if you haven't, if you think you cant or don't want to disassemble it, get a can of air, jam a paper clip through the radiator so it gets to the fan in such a way it cant spin (if you don't stop the fan from spinning it may get damaged from spinning too fast or even break a blade) and blow air in to it. It won't clean it as good as disassembling the laptop and brushing out the dust and so on, but it is better than nothing. Good luck :)

I doubt the cause would be running on the wrong graphics card, simply because I've had many problems myself with NVIDIA Optimus totally failing and games insisting on using the Intel HD (man, I hate optimus so much, wish I could just force everything to run on the nvidia card...) - but that's never resulted in overheating, just impossibly poor FPS.

I'm absolutely no tech expert so I can't tell if those are any good but I've heard there are Laptop Stands with additional external cooling which claim they can help increase a Laptops's longevity. Maybe that's something worth checking out.

Do u have any installed software for your GPUs except drivers? I mean third-party software or tools like ASUS GPU Tweak, software of Nvidia, etc.

Hi!

Sorry about your laptop problems. As mentioned previously, you might want to disassemble and clean it out.

But, you also should see how many frames are being rendered in your older games. Steam have a built in overlay which will tell you how many Frames Per Second you are getting on your games. You should probably keep that on, always.

Steam -> Settings -> In-Game -> Middle left 'In Game FPS counter

I noticed on some of my older games, my GPU would render thousands of FPS. My GPU would run hot and at 100%, and sometimes have annoying coil whine.

So, I installed a free tool called Dxtory. You run it before you start your game and tell it how many frames to limit it depending on your refresh rate. There are other programs as well you can use.

With Dxtory running, those older games would stop rendering 3000 FPS and start rendering 60 FPS, and my GPU ran cool without any whine.

AMD has a built in frame limiter as well, but to be honest I couldn't get it working on all my games so I still keep Dxtory around for ease of use.

Good luck!