Second RAM module is recognized but not being used

so hi everyone, so my laptop had 8GB ram(1600mhz) pre-installed and manjaro was working fine with that and I added another 4 GB stick with the same speed yesterday. the problem is my bios now shows 12GB ram and even manjaro Sudo dmidecode recognizes the another 4GB ram but it’s not being used as you can see in the free command
Outputs of dmidecode and free

dmidecode 3.3
Getting SMBIOS data from sysfs.
SMBIOS 2.8 present.

Handle 0x000B, DMI type 16, 23 bytes
Physical Memory Array
	Location: System Board Or Motherboard
	Use: System Memory
	Error Correction Type: None
	Maximum Capacity: 32 GB
	Error Information Handle: Not Provided
	Number Of Devices: 2

Handle 0x000C, DMI type 17, 40 bytes
Memory Device
	Array Handle: 0x000B
	Error Information Handle: Not Provided
	Total Width: 64 bits
	Data Width: 64 bits
	Size: 4 GB
	Form Factor: SODIMM
	Set: None
	Locator: DIMM 0
	Bank Locator: CHANNEL A
	Type: DDR3
	Type Detail: Synchronous Unbuffered (Unregistered)
	Speed: 1600 MT/s
	Manufacturer: Not Specified
	Serial Number: 00000000
	Asset Tag: Asset Tag:
	Part Number: Not Specified
	Rank: 1
	Configured Memory Speed: 800 MT/s
	Minimum Voltage: Unknown
	Maximum Voltage: Unknown
	Configured Voltage: Unknown

Handle 0x000D, DMI type 17, 40 bytes
Memory Device
	Array Handle: 0x000B
	Error Information Handle: Not Provided
	Total Width: 64 bits
	Data Width: 64 bits
	Size: 8 GB
	Form Factor: SODIMM
	Set: None
	Locator: DIMM 0
	Bank Locator: CHANNEL B
	Type: DDR3
	Type Detail: Synchronous Unbuffered (Unregistered)
	Speed: 1600 MT/s
	Manufacturer: Kingston
	Serial Number: 432A5F36
	Asset Tag: Asset Tag:
	Part Number: ACR16D3LS1KNG/8G
	Rank: 2
	Configured Memory Speed: 800 MT/s
	Minimum Voltage: Unknown
	Maximum Voltage: Unknown
	Configured Voltage: Unknown


free -h                                                                               Wednesday 05 May 2021 04:22:45 AM
               total        used        free      shared  buff/cache   available
Mem:           6.7Gi       1.6Gi       3.6Gi       206Mi       1.5Gi       4.7Gi
Swap:             0B          0B          0B

Hi @arshadpakkali, and welcome!

There is no real way to tell which of those RAM modules are being used or not, IIRC.

Also, I have 16GB of RAM but Linux has never used more than 10GB. Plainly because it has never needed any more. It won’t take more than what’s necessary.

So relax. It’s obviously because there is more than enough for it.

I think you are misunderstanding his question. He has 2 modules, 8 GB and 4 GB. His bios detects total RAM as 12 GB (8+4) which is correct but the distro still show’s total RAM as 6.7 GB. Even if the 4 GB RAM is not being used, it should still get detected and added to the total RAM in “free -h”
For example, I have 16 GB (8+8) and here is what my “free -h” looks like.

               total        used        free      shared  buff/cache   available
Mem:            15Gi       6.8Gi       1.7Gi       390Mi       7.0Gi       8.1Gi
Swap:          511Mi          0B       511Mi

Now coming back to OP’s problem, I don’t really know the solution but @arshadpakkali can you check what
sudo lshw -C memory
spits out for you?

2 Likes

Maybe because it allocates part of the RAM to iGPU (that is surely why you have 6.7G out of the 8G stick in the system), there is something weird happening when you boot the system on the detected amount of RAM. Maybe you have some option in the BIOS related to RAM but without the possibility of checking the BIOS ourselves it is hard to tell.

That might be possi8ble, but I was working from him saying that even dmidecode picked it up:

That, coupled with the fact that he say his BIOS picked it up:

led to my answer.

I don’t know what could be the problem, if any, if I misunderstood.

thanks for the reply everyone, and yeah what you’ve said is exactly my problem and the output of lshw is down below. so as you can see from here everything detects the memory but it doesn’t show up more than 6.
and I’ve even tried fill my ram up to 6 and as expected it gets to 6 and hangs rather than using the second stick


  *-firmware
       description: BIOS
       vendor: Insyde Corp.
       physical id: 0
       version: V1.15
       date: 07/06/2015
       size: 128KiB
       capacity: 8MiB
       capabilities: pci upgrade shadowing cdboot bootselect edd int13floppynec int13floppytoshiba int13floppy360 int13floppy1200 int13floppy720 int13floppy2880 int9keyboard int10video acpi usb biosbootspecification uefi
  *-cache:0
       description: L1 cache
       physical id: 5
       slot: L1 Cache
       size: 256KiB
       capacity: 256KiB
       clock: 1GHz (1.0ns)
       capabilities: pipeline-burst internal write-back unified
       configuration: level=1
  *-cache:1
       description: L2 cache
       physical id: 6
       slot: L2 Cache
       size: 4MiB
       capacity: 4MiB
       clock: 1GHz (1.0ns)
       capabilities: pipeline-burst internal write-back unified
       configuration: level=2
  *-memory
       description: System Memory
       physical id: b
       slot: System board or motherboard
       size: 12GiB
     *-bank:0
          description: SODIMM DDR3 Synchronous Unbuffered (Unregistered) 1600 MHz (0.6 ns)
          physical id: 0
          serial: 00000000
          slot: DIMM 0
          size: 4GiB
          width: 64 bits
          clock: 1600MHz (0.6ns)
     *-bank:1
          description: SODIMM DDR3 Synchronous Unbuffered (Unregistered) 1600 MHz (0.6 ns)
          product: ACR16D3LS1KNG/8G
          vendor: Kingston
          physical id: 1
          serial: 432A5F36
          slot: DIMM 0
          size: 8GiB
          width: 64 bits
          clock: 1600MHz (0.6ns)

ok I am not sure what the problem could be but it is possible the 4gb RAM stick is defunct. Especially the Serial for that stick is being shown as 00000000. Maybe you can check that by trying to boot with just the 4gb stick. And also try switching slots when you test just the 4 gb stick. Might lead us to narrowing down the problem if it is with the new 4gb stick.

2 Likes

Check dmesg or journalctl -b for memory…

hey thanks, everyone for helping out, so basically the RAM was defective after all that’s why it was causing trouble I tried only with the ram and it didn’t boot and swapped it for a new 4gb stick now everything works fine

2 Likes

This topic was automatically closed 15 days after the last reply. New replies are no longer allowed.