操作系统没有检测到我的所有 RAM

Question

我算是新手，如果这个问题已经得到很多解答，我很抱歉，但我第一次在新设置上安装了 ubuntu，它似乎只使用了我的 16 GB 中的 8.3 GB。

使用 ubuntu 21.04

但 Ubuntu 似乎知道这一点。以下是屏幕截图：

这是完整的内存检查：

*-firmware                
       description: BIOS
       vendor: American Megatrends Inc.
       physical id: 0
       version: P4.80
       date: 03/10/2021
       size: 64KiB
       capacity: 16MiB
       capabilities: pci upgrade shadowing cdboot bootselect socketedrom edd int13floppy1200 int13floppy720 int13floppy2880 int5printscreen int9keyboard int14serial int17printer acpi usb biosbootspecification uefi
  *-memory
       description: System Memory
       physical id: f
       slot: System board or motherboard
       size: 16GiB
     *-bank:0
          description: [empty]
          product: Unknown
          vendor: Unknown
          physical id: 0
          serial: Unknown
          slot: DIMM 0
     *-bank:1
          description: DIMM DDR4 Synchronous Unbuffered (Unregistered) 2133 MHz (0,5 ns)
          product: F4-3000C16-8GISB
          vendor: Unknown
          physical id: 1
          serial: 00000000
          slot: DIMM 1
          size: 8GiB
          width: 64 bits
          clock: 2133MHz (0.5ns)
     *-bank:2
          description: [empty]
          product: Unknown
          vendor: Unknown
          physical id: 2
          serial: Unknown
          slot: DIMM 0
     *-bank:3
          description: DIMM DDR4 Synchronous Unbuffered (Unregistered) 2133 MHz (0,5 ns)
          product: F4-3000C16-8GISB
          vendor: Unknown
          physical id: 3
          serial: 00000000
          slot: DIMM 1
          size: 8GiB
          width: 64 bits
          clock: 2133MHz (0.5ns)

我做错了什么？

提前致谢！