6 GB RAM is installed, but only 2 GB appears

[tuberculo]

Hi.
I have a weird problem.
My computer has 6 GB of RAM, but when I turn it on only 1.7 GB of RAM is available. If I run lshw, I can see that the all the RAM is installed. If I restart the system a few times, all the RAM is recognized properly.
Does anyone know the reason for this behavior?

free -m

             total       used       free     shared    buffers     cached
Mem:          1723        690       1033          0         78        231
-/+ buffers/cache:        381       1342
Swap:         9443          0       9443

sudo lshw -class memory

  *-firmware              
       descrição: BIOS
       fabricante: American Megatrends Inc.
       physical id: 0
       versão: P1.40
       date: 12/04/2012
       tamanho: 64KiB
       capacidade: 4032KiB
       capabilities: pci upgrade shadowing cdboot bootselect socketedrom edd int13floppy1200 int13floppy720 int13floppy2880 int5printscreen int9keyboard int14serial int17printer acpi usb biosbootspecification
  *-memory
       descrição: Memória do sistema
       physical id: 8
       slot: Placa do sistema ou placa-mãe
       tamanho: 6GiB
     *-bank:0
          descrição: DIMM DDR3 Síncrono 1333 MHz (0,8 ns)
          produto: 9905471-006.A00LF
          fabricante: Kingston
          physical id: 0
          serial: 65206C13
          slot: A1_DIMM0
          tamanho: 4GiB
          largura: 64 bits
          clock: 1333MHz (0.8ns)
     *-bank:1
          descrição: DIMM DDR3 Síncrono 1333 MHz (0,8 ns)
          produto: 9905402-179.A00LF
          fabricante: Kingston
          physical id: 1
          serial: 7E13B005
          slot: A1_DIMM1
          tamanho: 2GiB
          largura: 64 bits
          clock: 1333MHz (0.8ns)
  *-cache:0
       descrição: L1 cache
       physical id: f
       slot: L1 CACHE
       tamanho: 384KiB
       capacidade: 384KiB
       clock: 1GHz (1.0ns)
       capabilities: pipeline-burst internal write-back unified
  *-cache:1
       descrição: L2 cache
       physical id: 10
       slot: L2 CACHE
       tamanho: 3MiB
       capacidade: 3MiB
       clock: 1GHz (1.0ns)
       capabilities: pipeline-burst internal write-back unified

uname -a

Linux Principal-sala 3.2.0-36-generic #57-Ubuntu SMP Tue Jan 8 21:44:52 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

[sudodus]

So sometimes, after several reboots, all the memory will be grabbed by Ubuntu!

- Could it be a bad connection? Move the RAM cards a little, pull out and push in again and check if it helps.

- Check if you get some error with memtest (that you can start from the grub menu at boot). Run it for a long time, overnight if possible, to catch an error that might show up only once in a while. I suggest that you reboot until your computer (and memtest) will grab all the RAM.

[SeijiSensei]

It doesn't look like you're using the 64-bit version of the kernel. The 32-bit version cannot address all six gigabytes unless you have the -pae kernel installed, which uname does not report either.

Try booting from a 64-bit installation CD and run "Try Ubuntu". When it finishes loading, run free again. If you see all your memory, then you should consider upgrading to the 64-bit version.

[sudodus]

It doesn't look like you're using the 64-bit version of the kernel. The 32-bit version cannot address all six gigabytes unless you have the -pae kernel installed, which uname does not report either.

Try booting from a 64-bit installation CD and run "Try Ubuntu". When it finishes loading, run free again. If you see all your memory, then you should consider upgrading to the 64-bit version.

But in post #1 [s]he wrote

uname -a

Linux Principal-sala 3.2.0-36-generic #57-Ubuntu SMP Tue Jan 8 21:44:52 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

which indicates a 64-bit kernel (x86_64)

[SeijiSensei]

Sorry, I guess I didn't scroll right far enough.

[RAMChYLD]

Given that you have to restart a few times to have it detected properly...

Do this: Pay attention to the BIOS memory check screen, and see if it's detected properly there. To make the BIOS screen stay longer, turn off quick memory check. If yes, run Memtest86 whenever you notice the BIOS detecting less RAM than installed.

If no, then I'd suspect either RAM not seated properly, bad RAM, or (sometimes) PSU too weak to drive that many bars of RAM.

If yes, however, it may be a quirk with the firmware. Try upgrading your firmware and see if the problem goes away.

[Joao Lacerda]

Hi Tuberculo!

I have seen similar situation, and the problem was the sequence of
the memory on the banks, but for this I would recommend you to take a
look at the motherboard manual. if the memory are not placed correct
it can result on bad work.

Eu ja vi algo semelhante a isto e o problema era a sequencia que as
memorias estavam colocadas nos bancos, da uma olhada no site do
fabricante do seu computador na maioria das vezes tem um manual la
com as espicifações. num server que eu estou virando uma versao do
Ubuntu elas estao colocadas com espacos vazios geralmente este bancos
estao diferenciados com cores dois bancos pretos e dois brancos e se v
oce olhar as cores não estão juntas..



Boa sorte
Good luck.

Abraços.

João

[Lightning Dragon]

Hello,

I had the same problem, only with 4GB. For some reason it would only recognize 2 of the 4. I turned the computer off, unplugged the system, took out the RAM and then put them back in. However, if you have a mixed number like 1*2GB and 1*GB, put the biggest RAM in the first slot.

I say you should definitely consult the manual to your motherboard like Joao Lacerda suggested. Something could be wrong with how they are in or with your BIOS setup. The last thing it could be is that something is wrong with the RAM itself, not with the BIOS or the computer/Ubuntu. I have also read that letting your computer sit for about 5 minutes off with nothing plugged in (PSU) with the RAM out sort of resets it, so you could try that too.

[Yellow Pasque]

What kind of motherboard is it? Look at this if not sure:

sudo dmidecode

It's always best to use RAM on the mobo vendor's list (though this is not always feasible) and use RAM in matched pairs.

[tuberculo]

Thanks for all the replies.
I have already tried memtest, but I did not run it for a long time, I'll try that later.
If I want, I always manage to have 6 GB of RAM, but I have to reboot a few times. That's annoying. I think the problem may be in Ubuntu because, in BIOS, all the memory is recognized every time. The command lshw also recognizes 6 GB.
My motherboard is A55M-HVS. There are only two banks. I have already switched positions, with no result. I also tried BIOS update.
I will try Lightning Dragon's idea later.

dmidecode:

# dmidecode 2.11
SMBIOS 2.7 present.
19 structures occupying 1146 bytes.
Table at 0x000E9690.

Handle 0x0000, DMI type 0, 24 bytes
BIOS Information
	Vendor: American Megatrends Inc.
	Version: P1.40
	Release Date: 12/04/2012
	Address: 0xF0000
	Runtime Size: 64 kB
	ROM Size: 4096 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
		UEFI is supported
	BIOS Revision: 4.6

Handle 0x0001, DMI type 1, 27 bytes
System Information
	Manufacturer: To Be Filled By O.E.M.
	Product Name: To Be Filled By O.E.M.
	Version: To Be Filled By O.E.M.
	Serial Number: To Be Filled By O.E.M.
	UUID: 03000200-0400-0500-0006-000700080009
	Wake-up Type: Power Switch
	SKU Number: To Be Filled By O.E.M.
	Family: To Be Filled By O.E.M.

Handle 0x0002, DMI type 2, 15 bytes
Base Board Information
	Manufacturer: ASRock
	Product Name: A55M-HVS
	Version:                       
	Serial Number:                       
	Asset Tag:                       
	Features:
		Board is a hosting board
		Board is replaceable
	Location In Chassis:                       
	Chassis Handle: 0x0003
	Type: Motherboard
	Contained Object Handles: 0

Handle 0x0003, DMI type 3, 22 bytes
Chassis Information
	Manufacturer: To Be Filled By O.E.M.
	Type: Desktop
	Lock: Not Present
	Version: To Be Filled By O.E.M.
	Serial Number: To Be Filled By O.E.M.
	Asset Tag: To Be Filled By O.E.M.
	Boot-up State: Safe
	Power Supply State: Safe
	Thermal State: Safe
	Security Status: None
	OEM Information: 0x00000000
	Height: Unspecified
	Number Of Power Cords: 1
	Contained Elements: 0
	SKU Number: To be filled by O.E.M.

Handle 0x0004, DMI type 9, 17 bytes
System Slot Information
	Designation: PCI1
	Type: 32-bit PCI
	Current Usage: In Use
	Length: Short
	ID: 1
	Characteristics:
		3.3 V is provided
		Opening is shared
		PME signal is supported

Handle 0x0005, DMI type 9, 17 bytes
System Slot Information
	Designation: PCIE2
	Type: x16 PCI Express
	Current Usage: In Use
	Length: Short
	ID: 17
	Characteristics:
		3.3 V is provided
		Opening is shared
		PME signal is supported
	Bus Address: 0000:00:02.0

Handle 0x0006, DMI type 9, 17 bytes
System Slot Information
	Designation: PCIE3
	Type: x4 PCI Express
	Current Usage: In Use
	Length: Short
	ID: 18
	Characteristics:
		3.3 V is provided
		Opening is shared
		PME signal is supported
	Bus Address: 0000:00:04.0

Handle 0x0007, DMI type 11, 5 bytes
OEM Strings
	String 1: To Be Filled By O.E.M.

Handle 0x0008, DMI type 16, 23 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: 2

Handle 0x0009, DMI type 19, 31 bytes
Memory Array Mapped Address
	Starting Address: 0x00000000000
	Ending Address: 0x0017FFFFFFF
	Range Size: 6 GB
	Physical Array Handle: 0x0008
	Partition Width: 255

Handle 0x000A, DMI type 17, 34 bytes
Memory Device
	Array Handle: 0x0008
	Error Information Handle: Not Provided
	Total Width: 64 bits
	Data Width: 64 bits
	Size: 4096 MB
	Form Factor: DIMM
	Set: None
	Locator: A1_DIMM0
	Bank Locator: A1_BANK0
	Type: DDR3
	Type Detail: Synchronous
	Speed: 1333 MHz
	Manufacturer: Kingston        
	Serial Number: 65206C13  
	Asset Tag: A1_AssetTagNum0
	Part Number: 9905471-006.A00LF 
	Rank: 2
	Configured Clock Speed: 533 MHz

Handle 0x000B, DMI type 20, 35 bytes
Memory Device Mapped Address
	Starting Address: 0x00000000000
	Ending Address: 0x000FFFFFFFF
	Range Size: 4 GB
	Physical Device Handle: 0x000A
	Memory Array Mapped Address Handle: 0x0009
	Partition Row Position: 1

Handle 0x000C, DMI type 17, 34 bytes
Memory Device
	Array Handle: 0x0008
	Error Information Handle: Not Provided
	Total Width: 64 bits
	Data Width: 64 bits
	Size: 2048 MB
	Form Factor: DIMM
	Set: None
	Locator: A1_DIMM1
	Bank Locator: A1_BANK1
	Type: DDR3
	Type Detail: Synchronous
	Speed: 1333 MHz
	Manufacturer: Kingston        
	Serial Number: 7E13B005  
	Asset Tag: A1_AssetTagNum1
	Part Number: 9905402-179.A00LF 
	Rank: 1
	Configured Clock Speed: 533 MHz

Handle 0x000D, DMI type 20, 35 bytes
Memory Device Mapped Address
	Starting Address: 0x00100000000
	Ending Address: 0x0017FFFFFFF
	Range Size: 2 GB
	Physical Device Handle: 0x000C
	Memory Array Mapped Address Handle: 0x0009
	Partition Row Position: 1

Handle 0x000E, DMI type 32, 20 bytes
System Boot Information
	Status: No errors detected

Handle 0x000F, DMI type 7, 19 bytes
Cache Information
	Socket Designation: L1 CACHE
	Configuration: Enabled, Not Socketed, Level 1
	Operational Mode: Write Back
	Location: Internal
	Installed Size: 384 kB
	Maximum Size: 384 kB
	Supported SRAM Types:
		Pipeline Burst
	Installed SRAM Type: Pipeline Burst
	Speed: 1 ns
	Error Correction Type: Multi-bit ECC
	System Type: Unified
	Associativity: 2-way Set-associative

Handle 0x0010, DMI type 7, 19 bytes
Cache Information
	Socket Designation: L2 CACHE
	Configuration: Enabled, Not Socketed, Level 2
	Operational Mode: Write Back
	Location: Internal
	Installed Size: 3072 kB
	Maximum Size: 3072 kB
	Supported SRAM Types:
		Pipeline Burst
	Installed SRAM Type: Pipeline Burst
	Speed: 1 ns
	Error Correction Type: Multi-bit ECC
	System Type: Unified
	Associativity: 16-way Set-associative

Handle 0x0012, DMI type 4, 42 bytes
Processor Information
	Socket Designation: CPUSocket
	Type: Central Processor
	Family: S-Series
	Manufacturer: AMD
	ID: 10 0F 30 00 FF FB 8B 17
	Signature: Family 18, Model 1, Stepping 0
	Flags:
		FPU (Floating-point unit on-chip)
		VME (Virtual mode extension)
		DE (Debugging extension)
		PSE (Page size extension)
		TSC (Time stamp counter)
		MSR (Model specific registers)
		PAE (Physical address extension)
		MCE (Machine check exception)
		CX8 (CMPXCHG8 instruction supported)
		APIC (On-chip APIC hardware supported)
		SEP (Fast system call)
		MTRR (Memory type range registers)
		PGE (Page global enable)
		MCA (Machine check architecture)
		CMOV (Conditional move instruction supported)
		PAT (Page attribute table)
		PSE-36 (36-bit page size extension)
		CLFSH (CLFLUSH instruction supported)
		MMX (MMX technology supported)
		FXSR (FXSAVE and FXSTOR instructions supported)
		SSE (Streaming SIMD extensions)
		SSE2 (Streaming SIMD extensions 2)
		HTT (Multi-threading)
	Version: AMD A6-3500 APU with Radeon(tm) HD Graphics
	Voltage: 1.4 V
	External Clock: 100 MHz
	Max Speed: 2100 MHz
	Current Speed: 2100 MHz
	Status: Populated, Enabled
	Upgrade: Socket FM1
	L1 Cache Handle: 0x000F
	L2 Cache Handle: 0x0010
	L3 Cache Handle: Not Provided
	Serial Number: Not Specified
	Asset Tag: Not Specified
	Part Number: Not Specified
	Core Count: 3
	Core Enabled: 3
	Thread Count: 3
	Characteristics:
		64-bit capable

Handle 0x0013, DMI type 127, 4 bytes
End Of Table