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I think you might be making a confusion here.

I have an AMD Ryzen APU laptop also with 32GB of RAM and also with Windows 11 and yes just like in your case, it says in task manager GPU tab that 16GB are shared GPU memory, but like the name says, it's shared and not reserved, meaning the GPU can use up to 16GB of system RAM for textures and stuff but CPU apps are allowed to use nearly all the 32GB of RAM minus what you reserved exclusively for the GPU in BIOS and what the GPU is currently using on top of that.

And I know because I saw apps (not games) use nearly all my 32 gigs of ram.

But then why do my apps not use more than 16GB RAM? Everything together never surpasses 16GB RAM (maybe a bit, because it gets compressed). And in the meantime the GPUs show <1% RAM usage.

And Ubuntu has no issues with it, while Windows crawls on its knees once that limit is reached.

No idea. Maybe a driver issue. Have you played around with drivers? From Dell's website versus Intel's website.

Have you tried a fresh install of Windows 11 and not an upgrade from 10?

Ask on the Dell forums or subreddits. Maybe there's others out there with this issue.

Often that reserved memory is a soft limit that programs try to respect, but they can force allocate more. So what happens when you disable page file, close everything, open python3, and type this?

array20gb = bytearray(20 * 1024**3)

This should allocate 20GB of RAM to that process, starting with unused unreserved RAM, and then it should take your shared video memory after the unused unreserved RAM is allocated. If you get an error, then you know that reserved video RAM can't be used by programs.

Thanks! This is odd, and indeed it does start filling the RAM.

What could it then be what hinders the allocation of more than 50% under "normal operation". Initially it's fast, but over the course of a couple of hours if gets so low, that it takes around a minute to open a folder from the desktop via double-click while memory is at 50%. Temps are OK at that time and nothing is really getting used, like SSD is at 1-5%.

Probably system or driver issue resulting in lending/grabbing the maximum amount for no reason. Performance-wise, 4 GB dedicated video card gets no benefit from those extra gigabytes in RAM buffer anyway.

Do Quadro cards support some kind of “fat and slow” compatibility mode for software that demands giant memory size on a professional card to fit all the data there, and can wait to get the results? Maybe there's some switch you've toggled to enable “20 GB VRAM” mode?

You see? Bullshit issues like these is why I don't buy laptops with discrete GPUs anymore, especially Nvidia.

Are you sure the video memory is actually in use?

Like turn off Windows swap and use some application that will allocate around 24GB of RAM.

Windows always shows shared GPU memory as half the RAM, for example mine shows 64GB shared on my 128GB box, yet I have no problems loading up 90-100GB of VMs and running them full blast.

Now, the only thing that could be causing a problem here is if you're using any driver written by Dell themselves. They could very well be causing some kind of reservation bug that's not a direct windows issue itself.

runs just fine with Ubuntu

Maybe that is the answer?

I believe most (all?) machines allow you to configure this through the UEFI interface (pre-boot). Search your laptop model and you should find a way to change the amount of RAM dedicated to the integrated GPU.

Dell's BIOS has no option to change it, but it says that it has reserved 128MB for it.

As I said, Ubuntu has zero issues with handing 28GB+ RAM to applications, so this is convincingly a Windows thing and not something related to the BIOS.

While searching for a solution there's another person having this issue with a Gigabyte Z97-D3H-CF mainboard. He has 32GB RAM and half of it goes to "Shared Video Memory". I downloaded the manual and the relevant section reads

`Intel Processor Graphics Memory Allocation: Allows you to set the onboard graphics memory size. Options are: 32M~1024M. (Default: 64M)`

So the mainboard has no option for 16GB "Shared Video Memory", yet Windows 10 is causing this problem to him [0].

For me the "Works in Ubuntu" is what makes me disbelieve the BIOS-settings claims.

[0] https://answers.microsoft.com/en-us/windows/forum/all/change...

The reserved memory would show up as 'dedicated' memory. Shared is just the amount of host memory that can be assigned to graphics resources, which usually equals the system memory or some amount derived from it.

If the full amount of system memory isn't showing on Windows that's likely an unrelated issue you're experiencing (for example with UEFI/BIOS memory mapping mismatching whatever else) and it working on Linux implies that either Linux gets fed different memory layouts or it parses this broken case fine unlike Windows.

If applications aren't using all the memory, and it's also not showing up as cached, that's odd as Windows usually tends to target around 80% of physical memory usage (unless you're really not using that many apps or there's another driver issue going on). Different OSes account for memory usage differently, and there's rarely one single 'memory used' indicator in modern operating systems.

> If the full amount of system memory isn't showing on Windows that's likely an unrelated issue

Full amount of system memory is seen by Windows. It just refuses to hand out more than 16GB of RAM to it so I assume (maybe wrongly) that this is related to the other 16GB which the GPUs get assigned to but have no use for.

The memory graph in the task manager (Performance) never goes above 50%.

Usually you can modify the amount of RAM dedicated to the GPU in BIOS.