Of the built-in 4GB of RAM, LinuxMint 17.1 (rebecca) sees only 2988Mb. how so?

Question

linux

Good morning to all connoisseurs.
I recently decided instead of Windows to try Linux for myself. never worked with him, it became interesting. I installed LinuxMint 17.1 (x86_64) instead of Windows. after a couple of days of work, I noticed that something is not right, as my Linux works slower. went to sys. settings, and there on you, Memory Total - 2988Mb. although the laptop itself has 4Gb. what is that supposed to mean? and how to open the eyes of my system so that it can see all 4GB.
thanks for the advice and help

Answer 1

Go into the BIOS and reduce the amount of memory allocated for VGA.

Answer 2

What/what video cards are in the laptop?

Answer 3

Subsystem: Lenovo Device 5006
  Flags: bus master, fast devsel, latency 0, IRQ 44
  Memory at f0000000 (64-bit, non-prefetchable) [size=4M]
  Memory at e0000000 (64-bit, prefetchable) [size=256M]
  I/O ports at 4000 [size=64]
  Expansion ROM at <unassigned> [disabled]
  Capabilities: [90] MSI: Enable+ Count=1/1 Maskable- 64bit-
  Capabilities: [d0] Power Management version 2
  Capabilities: [a4] PCI Advanced Features
  Kernel driver in use: i915

может это поможет