While much of the PC industry has transitioned to 64-bit hardware and software, some older applications remain 32-bit (or a mix of 32-bit and 64-bit). 32-bit applications are not able to address more than 4GB of memory even if you run it on a 64-bit CPU and 64-bit operating system. If you have a graphics card with more than 4GB of video memory, a 32-bit application will not be able to read or write to more than 4GB of video memory. As a result, the amount of video memory the 32-bit application will report will be incorrect for graphics cards with more than 4GB of video memory.
Let us use an NVIDIA GeForce RTX 2080 Ti graphics card, which comes with 11GB of video memory, as an example. When a 32-bit application attempts to calculate the amount of video memory for the GeForce RTX 2080 Ti, it will do so in groups of 4GB. It will start by scanning the first 4GB of video memory and then proceed to read next 4GB and finally the remaining 3GB of video memory (4GB + 4GB + 3GB = 11GB).
Since the application only saw 3GB of video memory on the third scan, it will report the graphics card as having only 3GB of dedicated video memory as shown in the example below.
If you wish to look up the correct amount of video memory for your graphics card, we recommend opening up the NVIDIA Control Panel -> click on the System Information link on the bottom left hand corner of the window -> in the System Information window, look at the amount of video memory next to the words "Dedicated video memory:".