How to read the amount of RAM shared to GPU ?

It's looks like it defaults to 50% of physical memory, I have same results as Bree (16 GB system memory, 8GB shared to GPU)

There is usually some mechanism (via the BIOS or a jumper setting) to select the amount of system memory to use for graphics

Shared graphics memory - Wikipedia

You can also view shared memory in GPU adapter properties:
Settings -> System -> Display -> Advanced display settings -> Display adapter properties

Also WinKey + R and dxdiag, has more information.

Total amount of system memory that is dedicated or shared to the GPU. This number is calculated as follows:

Code:

TotalSystemMemoryAvailableForGraphics = MAX((TotalSystemMemory / 2), 64MB)

Second formula is a bit more complicated, here is breakdown:

The amount of system memory that is shared to the GPU. This number is calculated as follows:

Code:

SharedSystemMemory = MIN(MIN(SumOfCommitLimitOnAllApertureSegment, DXGK_DRIVERCAPS.ApertureSegmentCommitLimit), MaxSharedSystemMemory)

https://docs.microsoft.com/en-us/win...raphics-memory

Aperture Segment

An aperture segment is a global page table used to make discontinuous system memory pages appears contiguous from the perspective of a GPU engine.

https://docs.microsoft.com/en-us/win...y/gpu-segments

DXGK_DRIVERCAPS.ApertureSegmentCommitLimit

The maximum number of bytes of physical memory that the display miniport driver supports for mapping into an aperture segment. The video memory manager will not map more physical memory into an aperture segment than the limit that ApertureSegmentCommitLimit specifies.

https://docs.microsoft.com/en-us/win...xgk_drivercaps

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Conclusion is that final formula is either of the 2, which ever is less:

Code:

MIN(SumOfCommitLimitOnAllApertureSegment, DXGK_DRIVERCAPS.ApertureSegmentCommitLimit

OR

Code:

TotalSystemMemoryAvailableForGraphics - DedicatedSystemMemory

Which obviously depends on available physical memory installed on motherboard.