Why does it vote 512 mb on some memory sticks when thier dimensions is 497 sometimes even 475?

Answer:

Memory sticks reserve some space to store system info. That's thoroughly normal.
Sometimes regular file system information can appropriate up a few meg of memory so you will never get the full 512 meg.
because you enjoy onboard graphics is my guess.

onboard graphics use system memory to function.
The same reason floppies own 2.0 MB unformatted and 1.44mb formatted. The formatting provided the instruction that the operating system needs to read and use the stored information.