Why 16314 MB and not 16384 MB of RAM?

Question

RAM

Good afternoon and happy new year.
An incomprehensible situation arose, namely in aida 64 and windows itself, 16314 MB of RAM is shown, although, as far as I know, 16 GB = 16384 MB. What can be wrong? In bios it shows 16384 mb.
Memory:
CORSAIR DOMINATOR PLATINUM 16 GB 3000 MHZ

Answer 1

Part of the memory is reserved for equipment - a compatible video adapter mode (1 MB), an area for secure execution of SMM UEFI mode (~ 10 MB), a DMA controller for SATA and WiFi, structures for a USB controller, and so on. The system cannot use these areas (reserved at the BIOS stage), so it writes you the rest.

Answer 2

For example, there are areas mounted on I/O ports.