I didn't understand exactly how DVMT works, so I don't know if I need to increase the DVMT pre-allocated or not. When I buyed my pc, the data-sheet said that the vram of my computer was "up to 1GB", but when I checked the amount of dedicated video memory, the Windows showed "32MB". On bios I looked at DVMT and I can increase to 1024MB. But, reading about DVMT I learned that it's not necessary increasing to 1024MB to play games that need 1GB of vram (or less), the DVMT will allocate the amount of vram to the necessary to play the game. Is that true? I did understand right? (I can't afford an offboard GPU right now, I just want the 1GB of vram that the datasheet show, thanks!)
Yes, that is correct. The Intel HD Graphics driver for Windows will allocate as much memory as is required. This is limited to half of all available memory. For example, a PC with 8GB will make up to 4GB available for graphics usage, as required.
The only time that Windows users should increase the amount of dedicated graphics memory is if they have a poorly-written game that refuses to run unless it sees that a certain amount of dedicated memory is available. There is no performance advantage to dedicating additional memory for graphics.
Seems we have an issue then because everything through Microsoft will not run correctly irrespective of how much memory you have available if it's not correctly allocated as DVM
Since we can't access through BIOS and changing value in regedit does nothing what can be done.
As N. Scott Pearson mentioned, the Intel® HD Graphics will allocate as much memory as it requires to. This feature can be modified by the system manufacturer so the DVMT can increase or decrease as per the configuration set by the machine. You can always try with a Windows * clean installation in the case that the Microsoft® tools are not working properly or get in touch with them. Additionally, you can try to get in touch with your system manufacturer to check if there is any limitation set on your machine.