Hello!I have an ASUS G551JM with intel core-i7 4710hq (intel hd graphics 4600) and 16GB ram. Intel's website says that the hd graphics can have a maximum of 2GB virtual memory. However I can only allocate 512MB in the BIOS. Its dedicated memory is 128MB.
Can have a maximum of 2GB, that doesn't mean you'll actually be able to set it to 2GB on all computer systems.
The actual maximum you can assign to it is limited to whatever the BIOS allows.
Your laptop should have dual graphics (essentially two graphics processors):
1) Intel HD 4600 for general Windows tasks. (uses shared system memory)
2) Nvidia GTX 860M for games, & apps like Photoshop. (Nvidia GPU has dedicated memory).
Because your laptop has dual graphics, that's why maximum shared memory for the Intel GPU is limited to 512MB. That's all it needs for general Windows use. For better performance in games & graphics applications you are supposed to use the Nvidia GPU instead.