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.
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%.
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...