64bit Ubuntu 13.04 not recognizing additional 4GB RAM

Question

OS Info

sysadmin@linux01:~$ cat /etc/lsb-release 
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=13.04
DISTRIB_CODENAME=raring
DISTRIB_DESCRIPTION="Ubuntu 13.04"

sysadmin@linux01:~$ uname -a
Linux linux01 3.2.0-38-generic #61-Ubuntu SMP Tue Feb 19 12:18:21 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

sysadmin@linux01:~$ free -m
             total       used       free     shared    buffers     cached
Mem:          3887       3462        424          0        104       1172
-/+ buffers/cache:       2186       1701
Swap:        15259          0      15259

Hardware Info

id: firmware
description:    BIOS
vendor:     Intel Corp.
physical id:    0
version:    TCIBX10H.86A.0037.2010.0614.1712
date:   06/14/2010
size:   64KiB
capacity:   960KiB
capabilities:   pci upgrade shadowing cdboot bootselect socketedrom edd int13floppy1200 int13floppy720 int13floppy2880 int5printscreen int9keyboard int14serial int17printer acpi usb biosbootspecification
id: cpu
description:    CPU
product:    Intel(R) Core(TM) i5 CPU 760 @ 2.80GHz
vendor:     Intel Corp.
physical id:    4
bus info:   cpu@0
version:    Intel(R) Core(TM) i5 CPU 760 @ 2.80GHz

id: memory
description:    System Memory
physical id:    28
slot:   System board or motherboard
size:   8GiB
id: bank:0
description:    DIMM DDR3 Synchronous 1333 MHz (0.8 ns)
product:    JM1333KLN-4G
vendor:     Undefined
physical id:    0
serial:     0009B06F
slot:   CHANNEL A
size:   4GiB
width:  64 bits
clock:  1333MHz (0.8ns)

id: bank:2
description:    DIMM DDR3 Synchronous 1333 MHz (0.8 ns)
product:    JM1333KLH-4G
vendor:     Undefined
physical id:    2
serial:     0009EA2B
slot:   CHANNEL B
size:   4GiB
width:  64 bits
clock:  1333MHz (0.8ns)

Additional info from dmidecode

# dmidecode 2.11
SMBIOS 2.6 present.
79 structures occupying 3163 bytes.
Table at 0x000E9270.

Handle 0x0000, DMI type 0, 24 bytes
BIOS Information
    Vendor: Intel Corp.
    Version: TCIBX10H.86A.0037.2010.0614.1712
    Release Date: 06/14/2010
    Address: 0xF0000
    Runtime Size: 64 kB
    ROM Size: 1024 kB
    Characteristics:
        PCI is supported
        BIOS is upgradeable
        BIOS shadowing is allowed
        Boot from CD is supported
        Selectable boot is supported
        BIOS ROM is socketed
        EDD is supported
        5.25"/1.2 MB floppy services are supported (int 13h)
        3.5"/720 kB floppy services are supported (int 13h)
        3.5"/2.88 MB floppy services are supported (int 13h)
        Print screen service is supported (int 5h)
        8042 keyboard services are supported (int 9h)
        Serial services are supported (int 14h)
        Printer services are supported (int 17h)
        ACPI is supported
        USB legacy is supported
        BIOS boot specification is supported
        Targeted content distribution is supported

Handle 0x0028, 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: 0x0029
    Number Of Devices: 4

Handle 0x002B, DMI type 17, 28 bytes
Memory Device
    Array Handle: 0x0028
    Error Information Handle: 0x002C
    Total Width: 64 bits
    Data Width: 64 bits
    Size: 4096 MB
    Form Factor: DIMM
    Set: None
    Locator: CHANNEL A
    Bank Locator: CHANNEL A-DIMM 0
    Type: DDR3
    Type Detail: Synchronous
    Speed: 1333 MHz
    Manufacturer: Undefined       
    Serial Number: 0009B06F  
    Asset Tag: A1_AssetTagNum0
    Part Number: JM1333KLN-4G      
    Rank: 2
Handle 0x0031, DMI type 17, 28 bytes
Memory Device
    Array Handle: 0x0028
    Error Information Handle: 0x0032
    Total Width: 64 bits
    Data Width: 64 bits
    Size: 4096 MB
    Form Factor: DIMM
    Set: None
    Locator: CHANNEL B
    Bank Locator: CHANNEL B-DIMM 0
    Type: DDR3
    Type Detail: Synchronous
    Speed: 1333 MHz
    Manufacturer: Undefined       
    Serial Number: 0009EA2B  
    Asset Tag: A1_AssetTagNum2
    Part Number: JM1333KLH-4G      
    Rank: 1

As you can see from the above information, lshw can detech 8GB RAM on my system, but the OS cannot. Its a 64bit system. I have tried running a live CD , no luck. I have also installed the latest kernel, did upgrade-grub and have checked the /etc/default/grub config file. No issues there.

I have upgraded the BIOS as well.

Can anyone help resolve this issue?

Answer 1

It can be that (some DDR-)-RAM is newer than your BIOS of your machine. This means that BIOS is not recognizing your RAM correctly - so this RAM than stays "invisible" for Linux. A BIOS-update could help.

And overseen something : It can be, that your mainboard does not allow more than 8 Gibi ?! So additional 4 Gibi would not work. Ask the producer of your mainboard.