Laptop Dell com Ubuntu nao reconhece total de memoria

[marsselu]

Rapaziada,

Tenho um Dell Inspiron 5759 gen6 e o quadro é o seguine:
- instalei 2 pentes de 8G
- BIOS reconhece 1 pente com 8G, o outro só com 4G
- diagnostico Dell nao encontrou problemas
- comprei pente novo e aconteceu o mesmo
- pra piorar, dentro do ubuntu o monitor so reconhece 5G

Agradeço dicas magicas porque tá ph0d@

Valeu

=============
~ sudo lshw -C memory

  *-firmware               
       description: BIOS
       vendor: Dell Inc.
       physical id: 0
       version: 1.7.0
       date: 05/10/2019
       size: 64KiB
       capacity: 16MiB
       capabilities: pci pnp upgrade shadowing cdboot bootselect edd int13floppy1200 int13floppy720 int13floppy2880 int5printscreen int9keyboard int14serial int17printer acpi usb smartbattery biosbootspecification netboot uefi
  *-cache:0
       description: L1 cache
       physical id: 41
       slot: L1 Cache
       size: 64KiB
       capacity: 64KiB
       capabilities: synchronous internal write-back data
       configuration: level=1
  *-cache:1
       description: L1 cache
       physical id: 42
       slot: L1 Cache
       size: 64KiB
       capacity: 64KiB
       capabilities: synchronous internal write-back instruction
       configuration: level=1
  *-cache:2
       description: L2 cache
       physical id: 43
       slot: L2 Cache
       size: 512KiB
       capacity: 512KiB
       capabilities: synchronous internal write-back unified
       configuration: level=2
  *-cache:3
       description: L3 cache
       physical id: 44
       slot: L3 Cache
       size: 4MiB
       capacity: 4MiB
       capabilities: synchronous internal write-back unified
       configuration: level=3
  *-memory
       description: System Memory
       physical id: 46
       slot: System board or motherboard
       size: 12GiB
     *-bank:0
          description: SODIMM DDR3 Synchronous 1600 MHz (0,6 ns)
          product: 16KTF1G64HZ-1G6N1
          vendor: Micron
          physical id: 0
          serial: 12151215
          slot: DIMM A
          size: 8GiB
          width: 64 bits
          clock: 1600MHz (0.6ns)
     *-bank:1
          description: SODIMM DDR3 Synchronous 1600 MHz (0,6 ns)
          product: KNWMX1-ETB
          vendor: Kingston
          physical id: 1
          serial: 12121212
          slot: DIMM B
          size: 4GiB
          width: 64 bits
          clock: 1600MHz (0.6ns)
  *-memory UNCLAIMED
       description: Memory controller
       product: Sunrise Point-LP PMC
       vendor: Intel Corporation
       physical id: 1f.2
       bus info: pci@0000:00:1f.2
       version: 21
       width: 32 bits
       clock: 33MHz (30.3ns)
       capabilities: bus_master
       configuration: latency=0
       resources: memory:df324000-df327fff