Hello man i think the problem it is in the bios, this is i think max 2gb memory to card,
Try open bios when start PC go and find option shared memory you can give from Ram to your Gpu more memory
I think max 2gb, 512mb it's dedicated memory from your gpu but you can still add
Go hear maybe help you
"Total Available Video Memory" is the amount of memory that the graphics driver can use.
"Dedicated Video Memory" is the amount of memory that is present on the GPUs themselves and is handled by the GPU's memory controller.
"System Video Memory" is the amount of system memory that has been dedicated to graphics, this is handled by the system's memory controller.
"Shared System Memory" is the amount of system memory that can be used by graphics driver if it needs it. If it is not used by the graphics driver it may be used by something else (such as an application) and if it is all used by other applications, the driver will not be able to use it at all. This value is calculated as follows:
((TotalSystemMemory - 512) / 2) - SystemVideoMemory
The value "Total Available Graphics Memory" is the sum of all three. The amount of memory on the GPU itself as indicated by the graphics driver, plus the amount of system memory that has been dedicated to the GPU, plus the amount of shared system memory that the graphics driver can use.
The option that you see in your system settings actually controls the SystemVideoMemory which is the amount of system memory dedicated to use by a graphics processor and is almost always exclusive to IGPs.
To be clear, the "Shared System Memory" that you see in that window will always be a large number. Right now mine is sitting at 16,128MiB.
I have 32GiB of memory (32,768MiB), subtract from that 512MiB and the result is 32,256MiB. Divide that by two to get the 16,128MiB mentioned previously.
You cannot change this number, and it does not hinder your performance. However, you can change the SystemVideoMemory if you have an IGP, but it's recommended that you leave this number around 64MiB and let the graphics driver use the shared memory to make up the shortfall as needed. Feel free to experiment though