Wrong amount of memory displayed by free and kernel

I have just discovered an inconsistancy in my new server setup. When I issue the free -m command the output states that I have 1993 total memory available when I know for a fact that this machine has 6GB installed. The kernel agrees with this number but dmidecode does not. I am posting the output of the commands to make my problem clearer. Is this a kernel bug?

Code:

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$ free -m
            total      used      free    shared    buffers    cached
Mem:          1993        287      1705          0        77        103
-/+ buffers/cache:        105      1887
Swap:        2181          0      2181

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Code:

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dmesg | grep Memory
[    0.000000] Memory: 2022324k/2088512k available (6820k kernel code, 456k absent, 65732k reserved, 6347k data, 948k init)

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Code:

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sudo dmidecode

Handle 0x0002, DMI type 2, 10 bytes
Base Board Information
        Manufacturer:  EVGA
        Product Name: 132-BL-E758
        Version: Tylersburg
        Serial Number:
        Asset Tag:
        Features:
                Board is a hosting board

Handle 0x0005, DMI type 5, 28 bytes
Memory Controller Information
        Error Detecting Method: 8-bit Parity
        Error Correcting Capabilities:
                None
        Supported Interleave: One-way Interleave
        Current Interleave: One-way Interleave
        Maximum Memory Module Size: 2048 MB
        Maximum Total Memory Size: 12288 MB
        Supported Speeds:
                Other
        Supported Memory Types:
                DIMM
        Memory Module Voltage: 5.0 V
        Associated Memory Slots: 6
                0x0006
                0x0007
                0x0008
                0x0009
                0x000A
                0x000B
        Enabled Error Correcting Capabilities:
                None

Handle 0x0006, DMI type 6, 12 bytes
Memory Module Information
        Socket Designation: A0
        Bank Connections: 0 1
        Current Speed: Unknown
        Type: DIMM
        Installed Size: 2048 MB (Double-bank Connection)
        Enabled Size: 2048 MB (Double-bank Connection)
        Error Status: OK

Handle 0x0007, DMI type 6, 12 bytes
Memory Module Information
        Socket Designation: A1
        Bank Connections: None
        Current Speed: Unknown
        Type: Unknown
        Installed Size: Not Installed
        Enabled Size: Not Installed
        Error Status: OK

Handle 0x0008, DMI type 6, 12 bytes
Memory Module Information
        Socket Designation: A2
        Bank Connections: 4 5
        Current Speed: Unknown
        Type: DIMM
        Installed Size: 2048 MB (Double-bank Connection)
        Enabled Size: 2048 MB (Double-bank Connection)
        Error Status: OK

Handle 0x0009, DMI type 6, 12 bytes
Memory Module Information
        Socket Designation: A3
        Bank Connections: None
        Current Speed: Unknown
        Type: Unknown
        Installed Size: Not Installed
        Enabled Size: Not Installed
        Error Status: OK

Handle 0x000A, DMI type 6, 12 bytes
Memory Module Information
        Socket Designation: A4
        Bank Connections: 8 9
        Current Speed: Unknown
        Type: DIMM
        Installed Size: 2048 MB (Double-bank Connection)
        Enabled Size: 2048 MB (Double-bank Connection)
        Error Status: OK

Handle 0x000B, DMI type 6, 12 bytes
Memory Module Information
        Socket Designation: A5
        Bank Connections: None
        Current Speed: Unknown
        Type: Unknown
        Installed Size: Not Installed
        Enabled Size: Not Installed
        Error Status: OK

Handle 0x0023, DMI type 16, 15 bytes
Physical Memory Array
        Location: System Board Or Motherboard
        Use: System Memory
        Error Correction Type: None
        Maximum Capacity: 6 GB
        Error Information Handle: Not Provided
        Number Of Devices: 6

Handle 0x0024, DMI type 17, 27 bytes
Memory Device
        Array Handle: 0x0023
        Error Information Handle: Not Provided
        Total Width: 1 bits
        Data Width: 65508 bits
        Size: 2048 MB
        Form Factor: DIMM
        Set: None
        Locator: A0
        Bank Locator: Bank0/1
        Type: DDR2
        Type Detail: Synchronous
        Speed: Unknown
        Manufacturer: None
        Serial Number: None
        Asset Tag: None
        Part Number: None

Handle 0x0025, DMI type 17, 27 bytes
Memory Device
        Array Handle: 0x0023
        Error Information Handle: Not Provided
        Total Width: Unknown
        Data Width: Unknown
        Size: No Module Installed
        Form Factor: DIMM
        Set: None
        Locator: A1
        Bank Locator: Bank2/3
        Type: Unknown
        Type Detail: Unknown
        Speed: Unknown
        Manufacturer: None
        Serial Number: None
        Asset Tag: None
        Part Number: None

Handle 0x0026, DMI type 17, 27 bytes
Memory Device
        Array Handle: 0x0023
        Error Information Handle: Not Provided
        Total Width: 1 bits
        Data Width: 65508 bits
        Size: 2048 MB
        Form Factor: DIMM
        Set: None
        Locator: A2
        Bank Locator: Bank4/5
        Type: DDR2
        Type Detail: Synchronous
        Speed: Unknown
        Manufacturer: None
        Serial Number: None
        Asset Tag: None
        Part Number: None

Handle 0x0027, DMI type 17, 27 bytes
Memory Device
        Array Handle: 0x0023
        Error Information Handle: Not Provided
        Total Width: Unknown
        Data Width: Unknown
        Size: No Module Installed
        Form Factor: DIMM
        Set: None
        Locator: A3
        Bank Locator: Bank6/7
        Type: Unknown
        Type Detail: Unknown
        Speed: Unknown
        Manufacturer: None
        Serial Number: None
        Asset Tag: None
        Part Number: None

Handle 0x0028, DMI type 17, 27 bytes
Memory Device
        Array Handle: 0x0023
        Error Information Handle: Not Provided
        Total Width: 1 bits
        Data Width: 65508 bits
        Size: 2048 MB
        Form Factor: DIMM
        Set: None
        Locator: A4
        Bank Locator: Bank8/9
        Type: DDR2
        Type Detail: Synchronous
        Speed: Unknown
        Manufacturer: None
        Serial Number: None
        Asset Tag: None
        Part Number: None

Handle 0x0029, DMI type 17, 27 bytes
Memory Device
        Array Handle: 0x0023
        Error Information Handle: Not Provided
        Total Width: Unknown
        Data Width: Unknown
        Size: No Module Installed
        Form Factor: DIMM
        Set: None
        Locator: A5
        Bank Locator: Bank10/11
        Type: Unknown
        Type Detail: Unknown
        Speed: Unknown
        Manufacturer: None
        Serial Number: None
        Asset Tag: None
        Part Number: None

Handle 0x002A, DMI type 18, 23 bytes
32-bit Memory Error Information
        Type: Other
        Granularity: Other
        Operation: Other
        Vendor Syndrome: Unknown
        Memory Array Address: Unknown
        Device Address: Unknown
        Resolution: Unknown

Handle 0x002B, DMI type 19, 15 bytes
Memory Array Mapped Address
        Starting Address: 0x00000000000
        Ending Address: 0x0017FFFFFFF
        Range Size: 6 GB
        Physical Array Handle: 0x0024
        Partition Width: 1

Handle 0x002C, DMI type 20, 19 bytes
Memory Device Mapped Address
        Starting Address: 0x00000000000
        Ending Address: 0x0007FFFFFFF
        Range Size: 2 GB
        Physical Device Handle: 0x0025
        Memory Array Mapped Address Handle: 0x002B
        Partition Row Position: 1

Handle 0x002D, DMI type 20, 19 bytes
Memory Device Mapped Address
        Starting Address: 0x00000000000
        Ending Address: 0x000000003FF
        Range Size: 1 kB
        Physical Device Handle: 0x0026
        Memory Array Mapped Address Handle: 0x002B
        Partition Row Position: 1

Handle 0x002E, DMI type 20, 19 bytes
Memory Device Mapped Address
        Starting Address: 0x00080000000
        Ending Address: 0x000FFFFFFFF
        Range Size: 2 GB
        Physical Device Handle: 0x0027
        Memory Array Mapped Address Handle: 0x002B
        Partition Row Position: 1

Handle 0x002F, DMI type 20, 19 bytes
Memory Device Mapped Address
        Starting Address: 0x00000000000
        Ending Address: 0x000000003FF
        Range Size: 1 kB
        Physical Device Handle: 0x0028
        Memory Array Mapped Address Handle: 0x002B
        Partition Row Position: 1

Handle 0x0030, DMI type 20, 19 bytes
Memory Device Mapped Address
        Starting Address: 0x00100000000
        Ending Address: 0x0017FFFFFFF
        Range Size: 2 GB
        Physical Device Handle: 0x0029
        Memory Array Mapped Address Handle: 0x002B
        Partition Row Position: 1

Handle 0x0031, DMI type 20, 19 bytes
Memory Device Mapped Address
        Starting Address: 0x00000000000
        Ending Address: 0x000000003FF
        Range Size: 1 kB
        Physical Device Handle: 0x002A
        Memory Array Mapped Address Handle: 0x002B
        Partition Row Position: 1

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what kernel are you using?

uname -a

Looks right for 2GB of ram, but not 6GB. free -m displays the memory free in megabytes, and dmesg is showing in kb.

If you have two or three sticks of memory and only one is being seen - check the bios to make sure it is seeing all the sticks, which is likely if lshw shows them.

What version of Ubuntu are you using?

What does top show?

Seems I should have started from the beginning and checked the BIOS first. #-o It was showing only 2GB of memory also, so I removed all the memory sticks and put them back in. Now everything is showing 6GB. At least now I can continue with the BTRFS experiment.