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I've been dual-booting my laptop for about six months now, on one side Ubuntu 14.04 and on the other Windows 7. When I bought this computer two and a half years ago, it had 8GB of ram. My Windows operating system says I have 8GB of ram. However, Ubuntu recognizes only 4GB of ram. I know it has been like this since I started dual-booting, but I never really tried doing much about it today. I looked in a few places online but did not find much help. To save us all some trouble of back and forth of command results and computer statistics, I'll just save us all the time and provide it all now.


Computer:

Toshiba Satellite L655-S158


Operating System:

Ubuntu 14.04 LTS


uname -m

x86_64

cat /proc/meminfo

MemTotal:        3843080 kB
MemFree:          503960 kB
Buffers:         1079968 kB
Cached:          1264284 kB
SwapCached:            0 kB
Active:          1072992 kB
Inactive:        2027536 kB
Active(anon):     502716 kB
Inactive(anon):   410464 kB
Active(file):     570276 kB
Inactive(file):  1617072 kB
Unevictable:          32 kB
Mlocked:              32 kB
SwapTotal:       6291452 kB
SwapFree:        6291452 kB
Dirty:                 0 kB
Writeback:             0 kB
AnonPages:        756348 kB
Mapped:           252040 kB
Shmem:            156904 kB
Slab:             151668 kB
SReclaimable:     121160 kB
SUnreclaim:        30508 kB
KernelStack:        3880 kB
PageTables:        30508 kB
NFS_Unstable:          0 kB
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:     8212992 kB
Committed_AS:    3836276 kB
VmallocTotal:   34359738367 kB
VmallocUsed:      546060 kB
VmallocChunk:   34359183836 kB
HardwareCorrupted:     0 kB
AnonHugePages:     69632 kB
HugePages_Total:       0
HugePages_Free:        0
HugePages_Rsvd:        0
HugePages_Surp:        0
Hugepagesize:       2048 kB
DirectMap4k:       61696 kB
DirectMap2M:     3926016 kB

sudo dmidecode --type memory

# dmidecode 2.12
SMBIOS 2.6 present.

Handle 0x0019, DMI type 16, 15 bytes
Physical Memory Array
    Location: System Board Or Motherboard
    Use: System Memory
    Error Correction Type: None
    Maximum Capacity: 16 GB
    Error Information Handle: No Error
    Number Of Devices: 2

Handle 0x001A, DMI type 17, 28 bytes
Memory Device
    Array Handle: 0x0019
    Error Information Handle: 0x001C
    Total Width: 64 bits
    Data Width: 64 bits
    Size: 2048 MB
    Form Factor: SODIMM
    Set: None
    Locator: DIMM0
    Bank Locator: BANK 0
    Type: DDR3
    Type Detail: Synchronous
    Speed: 1067 MHz
    Manufacturer: Not Specified
    Serial Number: 960F424C
    Asset Tag: Unknown
    Part Number: M471B5673FH0-CF8  
    Rank: 2

Handle 0x001B, DMI type 6, 12 bytes
Memory Module Information
    Socket Designation: DIMM0
    Bank Connections: None
    Current Speed: Unknown
    Type: DIMM
    Installed Size: 2048 MB (Single-bank Connection)
    Enabled Size: 2048 MB (Single-bank Connection)
    Error Status: OK

Handle 0x001E, DMI type 17, 28 bytes
Memory Device
    Array Handle: 0x0019
    Error Information Handle: Not Provided
    Total Width: 8 bits
    Data Width: 8 bits
    Size: No Module Installed
    Form Factor: DIMM
    Set: None
    Locator: DIMM1
    Bank Locator: BANK 1
    Type: DDR3
    Type Detail: Synchronous
    Speed: 1067 MHz
    Manufacturer: Not Specified
    Serial Number: 00000000
    Asset Tag: Unknown
    Part Number: Not Specified
    Rank: 1

Handle 0x001F, DMI type 6, 12 bytes
Memory Module Information
    Socket Designation: DIMM1
    Bank Connections: None
    Current Speed: Unknown
    Type: DIMM
    Installed Size: Not Installed
    Enabled Size: Not Installed
    Error Status: OK

Handle 0x0021, DMI type 17, 28 bytes
Memory Device
    Array Handle: 0x0019
    Error Information Handle: 0x0023
    Total Width: 64 bits
    Data Width: 64 bits
    Size: 2048 MB
    Form Factor: SODIMM
    Set: None
    Locator: DIMM1
    Bank Locator: BANK 2
    Type: DDR3
    Type Detail: Synchronous
    Speed: 1067 MHz
    Manufacturer: Not Specified
    Serial Number: 960F4251
    Asset Tag: Unknown
    Part Number: M471B5673FH0-CF8  
    Rank: 2

Handle 0x0022, DMI type 6, 12 bytes
Memory Module Information
    Socket Designation: DIMM1
    Bank Connections: None
    Current Speed: Unknown
    Type: DIMM
    Installed Size: 2048 MB (Single-bank Connection)
    Enabled Size: 2048 MB (Single-bank Connection)
    Error Status: OK

Handle 0x0025, DMI type 17, 28 bytes
Memory Device
    Array Handle: 0x0019
    Error Information Handle: Not Provided
    Total Width: 8 bits
    Data Width: 8 bits
    Size: No Module Installed
    Form Factor: DIMM
    Set: None
    Locator: DIMM3
    Bank Locator: BANK 3
    Type: DDR3
    Type Detail: Synchronous
    Speed: 1067 MHz
    Manufacturer: Not Specified
    Serial Number: 00000000
    Asset Tag: Unknown
    Part Number: Not Specified
    Rank: 1

Handle 0x0026, DMI type 6, 12 bytes
Memory Module Information
    Socket Designation: DIMM3
    Bank Connections: None
    Current Speed: Unknown
    Type: DIMM
    Installed Size: Not Installed
    Enabled Size: Not Installed
    Error Status: OK

Handle 0x002A, DMI type 5, 20 bytes
Memory Controller Information
    Error Detecting Method: None
    Error Correcting Capabilities:
        Unknown
        None
    Supported Interleave: One-way Interleave
    Current Interleave: One-way Interleave
    Maximum Memory Module Size: 8192 MB
    Maximum Total Memory Size: 16384 MB
    Supported Speeds:
        Other
    Supported Memory Types:
        Other
    Memory Module Voltage: Unknown
    Associated Memory Slots: 2
        0x001B
        0x0022
    Enabled Error Correcting Capabilities:
        None

free -m

             total       used       free     shared    buffers     cached
Mem:          3753       3299        453        155       1055       1245
-/+ buffers/cache:        998       2754
Swap:         6143          0       6143

So, how do I get my computer to recognize the other 4GB?

  • Can you reboot and run memtest or test the ram in an alternate OS. – Panther Nov 6 '14 at 1:11
  • Do you have the 64 bit version of Ubuntu? – Marty Fried Nov 6 '14 at 2:12
  • Did you install the latest version of your BIOS/EFI? It is not uncommon, that the wrong memory size is reported to the OS by it. Linux usually values this information until told otherwise. In Windows there are often "drivers" that work around the bug on the OS level. – Klaus D. Nov 6 '14 at 9:33
  • I just checked my BIOS and it did in fact also not recognise my 8GB of memory, telling me I had only 4GB (4096 MB). If I was to update my BIOS, how would I go about doing that on Linux? – Drewtabaga Jan 26 '15 at 5:49
1

You can check what Ubuntu version are you running via

uname -a

If you have the 32bit version (i386) you have to install the 64bit version (x86_64) to let your computer address more that 4GiB (Gibibytes) of RAM.

This is due to tecnhnical limitations of the 32bit width, as explained at the beginning of this very nice Wikipedia page.

Please note that similar limitations apply also for 64bit-wide architecture. Indeed, you cannot address more than 16 EiB (Exbibytes) of information.

|improve this answer|||||
  • uname -a 13.0-24-generic #46-Ubuntu SMP Thu Apr 10 19:11:08 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux – Drewtabaga Nov 8 '14 at 18:19

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