Только часть моей доступной RAM

free -h шоу только отделяются моей RAM (~ 5 ГБ), хотя я установил 8 ГБ.

dmidecode:

# dmidecode 3.0
Getting SMBIOS data from sysfs.
SMBIOS 2.7 present.

Handle 0x0007, DMI type 16, 23 bytes
Physical Memory Array
    Location: System Board Or Motherboard
    Use: System Memory
    Error Correction Type: None
    Maximum Capacity: 16 GB
    Error Information Handle: Not Provided
    Number Of Devices: 2

Handle 0x0008, DMI type 17, 34 bytes
Memory Device
    Array Handle: 0x0007
    Error Information Handle: Not Provided
    Total Width: 64 bits
    Data Width: 64 bits
    Size: 4096 MB
    Form Factor: SODIMM
    Set: None
    Locator: ChannelA-DIMM0
    Bank Locator: BANK 0
    Type: DDR3
    Type Detail: Synchronous
    Speed: 1600 MHz
    Manufacturer: Samsung
    Serial Number: 949678E8
    Asset Tag: 9876543210
    Part Number: M471B5273DH0-CK0  
    Rank: Unknown
    Configured Clock Speed: 1600 MHz

Handle 0x0009, DMI type 17, 34 bytes
Memory Device
    Array Handle: 0x0007
    Error Information Handle: Not Provided
    Total Width: 64 bits
    Data Width: 64 bits
    Size: 4096 MB
    Form Factor: SODIMM
    Set: None
    Locator: ChannelB-DIMM0
    Bank Locator: BANK 2
    Type: DDR3
    Type Detail: Synchronous
    Speed: 1600 MHz
    Manufacturer: Kingston
    Serial Number: 5E3C8BBE
    Asset Tag: 9876543210
    Part Number: 99U5469-048.A00LF 
    Rank: Unknown
    Configured Clock Speed: 1600 MHz

free -h:

              total        used        free      shared  buff/cache   available
Mem:           5,6G        4,4G        254M        355M        1,0G        576M
Swap:          7,7G        335M        7,4G

uname:

Linux edge 4.4.0-63-generic #84-Ubuntu SMP Wed Feb 1 17:20:32 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

Кто-либо знает, что ho устраняет эту проблему?