我有 AMD FX-8350 处理器和技嘉 970 Gaming G1 主板。两者都支持 8+8 GB RAM。但是当我安装 Ubuntu 16.06 LTS 时，只检测到 8 GB RAM。虽然我的 BIOS 显示 16GB RAM。任何人都可以帮忙找出问题所在。
输出sudo lshw -class memory（删除了固件和 CPU 缓存条目）：
*-memory
description: System Memory
physical id: 2c
slot: System board or motherboard
size: 16GiB
*-bank:0
description: DIMM Synchronous [empty]
product: Dimm0_PartNum
vendor: Dimm0_Manufacturer
physical id: 0
serial: Dimm0_SerNum
slot: Node0_Dimm0
*-bank:1
description: DIMM DDR3 Synchronous 800 MHz (1.2 ns)
product: CT102464BD160
vendor: Undefined
physical id: 1
serial: xxxxxx
slot: Node0_Dimm1
size: 8GiB
width: 64 bits
clock: 800MHz (1.2ns)
*-bank:2
description: DIMM DDR3 Synchronous 800 MHz (1.2 ns)
product: CT102464BD160
vendor: Undefined
physical id: 2
serial: xxxxxxx
slot: Node0_Dimm2
size: 8GiB
width: 64 bits
clock: 800MHz (1.2ns)
*-bank:3
description: DIMM Synchronous [empty]
product: Dimm3_PartNum
vendor: Dimm3_Manufacturer
physical id: 3
serial: Dimm3_SerNum
slot: Node0_Dimm3
的输出free：
total used free shared buff/cache available
Mem: 8200928 1225344 4568440 26436 2407144 6636296
Swap: 8350716 0 8350716
的输出sudo dmidecode -t memory：
# dmidecode 3.0
Getting SMBIOS data from sysfs.
SMBIOS 2.7 present.
Handle 0x0008, DMI type 5, 24 bytes
Memory Controller Information
Error Detecting Method: 64-bit ECC
Error Correcting Capabilities:
None
Supported Interleave: One-way Interleave
Current Interleave: One-way Interleave
Maximum Memory Module Size: 2048 MB
Maximum Total Memory Size: 8192 MB
Supported Speeds:
70 ns
60 ns
Supported Memory Types:
DIMM
SDRAM
Memory Module Voltage: 3.3 V
Associated Memory Slots: 4
0x0009
0x000A
0x000B
0x000C
Enabled Error Correcting Capabilities:
None
Handle 0x0009, DMI type 6, 12 bytes
Memory Module Information
Socket Designation: DIMM0
Bank Connections: 0 1
Current Speed: 60 ns
Type: DIMM SDRAM
Installed Size: 536870912 MB (Single-bank Connection)
Enabled Size: 536870912 MB (Single-bank Connection)
Error Status: OK
Handle 0x000A, DMI type 6, 12 bytes
Memory Module Information
Socket Designation: DIMM1
Bank Connections: 2 3
Current Speed: 60 ns
Type: DIMM SDRAM
Installed Size: 536870912 MB (Single-bank Connection)
Enabled Size: 536870912 MB (Single-bank Connection)
Error Status: OK
Handle 0x000B, DMI type 6, 12 bytes
Memory Module Information
Socket Designation: DIMM2
Bank Connections: 4 5
Current Speed: 60 ns
Type: DIMM SDRAM
Installed Size: 536870912 MB (Single-bank Connection)
Enabled Size: 536870912 MB (Single-bank Connection)
Error Status: OK
Handle 0x000C, DMI type 6, 12 bytes
Memory Module Information
Socket Designation: DIMM3
Bank Connections: 6 7
Current Speed: 60 ns
Type: DIMM SDRAM
Installed Size: 536870912 MB (Single-bank Connection)
Enabled Size: 536870912 MB (Single-bank Connection)
Error Status: OK
Handle 0x002C, 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: 4
Handle 0x002E, DMI type 17, 34 bytes
Memory Device
Array Handle: 0x002C
Error Information Handle: Not Provided
Total Width: Unknown
Data Width: 64 bits
Size: No Module Installed
Form Factor: DIMM
Set: None
Locator: Node0_Dimm0
Bank Locator: Node0_Bank0
Type: Unknown
Type Detail: Synchronous
Speed: Unknown
Manufacturer: Dimm0_Manufacturer
Serial Number: Dimm0_SerNum
Asset Tag: Dimm0_AssetTag
Part Number: Dimm0_PartNum
Rank: Unknown
Configured Clock Speed: Unknown
Handle 0x0030, DMI type 17, 34 bytes
Memory Device
Array Handle: 0x002C
Error Information Handle: Not Provided
Total Width: 64 bits
Data Width: 64 bits
Size: 8192 MB
Form Factor: DIMM
Set: None
Locator: Node0_Dimm1
Bank Locator: Node0_Bank0
Type: DDR3
Type Detail: Synchronous Unbuffered (Unregistered)
Speed: 800 MHz
Manufacturer: Undefined
Serial Number: E059EC0B
Asset Tag: Dimm1_AssetTag
Part Number: CT102464BD160
Rank: 2
Configured Clock Speed: 800 MHz
Handle 0x0032, DMI type 17, 34 bytes
Memory Device
Array Handle: 0x002C
Error Information Handle: Not Provided
Total Width: 64 bits
Data Width: 64 bits
Size: 8192 MB
Form Factor: DIMM
Set: None
Locator: Node0_Dimm2
Bank Locator: Node0_Bank0
Type: DDR3
Type Detail: Synchronous Unbuffered (Unregistered)
Speed: 800 MHz
Manufacturer: Undefined
Serial Number: E059EC5D
Asset Tag: Dimm2_AssetTag
Part Number: CT102464BD160
Rank: 2
Configured Clock Speed: 800 MHz
Handle 0x0034, DMI type 17, 34 bytes
Memory Device
Array Handle: 0x002C
Error Information Handle: Not Provided
Total Width: Unknown
Data Width: 64 bits
Size: No Module Installed
Form Factor: DIMM
Set: None
Locator: Node0_Dimm3
Bank Locator: Node0_Bank0
Type: Unknown
Type Detail: Synchronous
Speed: Unknown
Manufacturer: Dimm3_Manufacturer
Serial Number: Dimm3_SerNum
Asset Tag: Dimm3_AssetTag
Part Number: Dimm3_PartNum
Rank: Unknown
Configured Clock Speed: Unknown
free交换内存插槽后的输出：
total used free shared buff/cache available
Mem: 16458456 807424 14920452 23940 730580 15312852
Swap: 8350716 0 8350716
您有 4 个内存插槽，编号为 0、1、2 和 3。
通常（至少在双通道 RAM 主板上），如果您只使用 4 个插槽中的 2 个，则 RAM 块插入偶数或奇数插槽。通常插座也有两种不同的颜色来表示这一点。
正如输出所sudo lshw -c memory建议的那样，您的积木放置在插槽 1 和 2 中。
我建议改变它们的位置，使两块砖都在偶数 (0, 2) 或奇数 (1, 3) 插槽中。请查阅您的主板手册以了解确切的推荐顺序。