今天我安装了新的 8GB RAM，替换了旧的 4GB RAM，但 Ubuntu 和 Windows 10 都无法识别它（我有双操作系统）。
现在我只识别了 4GB，因为我没有替换它们两个。
我运行了 memtest86+ 测试，一切正常，没有错误。我在 memtest86+ 中的 SPD 部分看到了新的 RAM 信息。
结果如下：
dmesg | grep memory命令：
[ 0.000000] Scanning 1 areas for low memory corruption
[ 0.000000] Base memory trampoline at [ffff880000096000] 96000 size 24576
[ 0.000000] Early memory node ranges
[ 0.000000] Reserving Intel graphics stolen memory at 0xcbe00000-0xcfdfffff
[ 0.000000] PM: Registered nosave memory: [mem 0x00000000-0x00000fff]
[ 0.000000] PM: Registered nosave memory: [mem 0x0009c000-0x0009cfff]
[ 0.000000] PM: Registered nosave memory: [mem 0x0009d000-0x0009ffff]
[ 0.000000] PM: Registered nosave memory: [mem 0x000a0000-0x000dffff]
[ 0.000000] PM: Registered nosave memory: [mem 0x000e0000-0x000fffff]
[ 0.000000] PM: Registered nosave memory: [mem 0xb9985000-0xb998bfff]
[ 0.000000] PM: Registered nosave memory: [mem 0xba214000-0xba497fff]
[ 0.000000] PM: Registered nosave memory: [mem 0xc98eb000-0xc9afffff]
[ 0.000000] PM: Registered nosave memory: [mem 0xc9e1a000-0xcab28fff]
[ 0.000000] PM: Registered nosave memory: [mem 0xcab29000-0xcaffefff]
[ 0.000000] PM: Registered nosave memory: [mem 0xcb000000-0xcbbfffff]
[ 0.000000] PM: Registered nosave memory: [mem 0xcbc00000-0xcfdfffff]
[ 0.000000] PM: Registered nosave memory: [mem 0xcfe00000-0xf7ffffff]
[ 0.000000] PM: Registered nosave memory: [mem 0xf8000000-0xfbffffff]
[ 0.000000] PM: Registered nosave memory: [mem 0xfc000000-0xfebfffff]
[ 0.000000] PM: Registered nosave memory: [mem 0xfec00000-0xfec00fff]
[ 0.000000] PM: Registered nosave memory: [mem 0xfec01000-0xfecfffff]
[ 0.000000] PM: Registered nosave memory: [mem 0xfed00000-0xfed03fff]
[ 0.000000] PM: Registered nosave memory: [mem 0xfed04000-0xfed1bfff]
[ 0.000000] PM: Registered nosave memory: [mem 0xfed1c000-0xfed1ffff]
[ 0.000000] PM: Registered nosave memory: [mem 0xfed20000-0xfedfffff]
[ 0.000000] PM: Registered nosave memory: [mem 0xfee00000-0xfee00fff]
[ 0.000000] PM: Registered nosave memory: [mem 0xfee01000-0xfeffffff]
[ 0.000000] PM: Registered nosave memory: [mem 0xff000000-0xffffffff]
[ 0.032437] Initializing cgroup subsys memory
[ 0.034019] Freeing SMP alternatives memory: 28K (ffffffff820b2000 - ffffffff820b9000)
[ 0.951478] Freeing initrd memory: 40740K (ffff88003305e000 - ffff880035827000)
[ 0.951727] Scanning for low memory corruption every 60 seconds
[ 1.023211] Freeing unused kernel memory: 1476K (ffffffff81f41000 - ffffffff820b2000)
[ 1.023543] Freeing unused kernel memory: 1872K (ffff88000182c000 - ffff880001a00000)
[ 1.023877] Freeing unused kernel memory: 176K (ffff880001dd4000 - ffff880001e00000)
dmidecode --type memory命令：
# dmidecode 3.0
/sys/firmware/dmi/tables/smbios_entry_point: Permission denied
Scanning /dev/mem for entry point.
/dev/mem: Permission denied
l@l:~$ sudo dmidecode --type memory
[sudo] password for l:
# dmidecode 3.0
Getting SMBIOS data from sysfs.
SMBIOS 2.7 present.
Handle 0x000C, 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 0x000D, DMI type 17, 34 bytes
Memory Device
Array Handle: 0x000C
Error Information Handle: Not Provided
Total Width: 64 bits
Data Width: 64 bits
Size: 4096 MB
Form Factor: SODIMM
Set: None
Locator: ChannelA-DIMM0
Bank Locator: BANK 0
Type: DDR3
Type Detail: Synchronous
Speed: 1600 MHz
Manufacturer: Hynix/Hyundai
Serial Number: 00000000
Asset Tag: 9876543210
Part Number:
Rank: 1
Configured Clock Speed: 1600 MHz
Handle 0x000F, DMI type 17, 34 bytes
Memory Device
Array Handle: 0x000C
Error Information Handle: Not Provided
Total Width: Unknown
Data Width: Unknown
Size: No Module Installed
Form Factor: DIMM
Set: None
Locator: ChannelA-DIMM1
Bank Locator: BANK 1
Type: Unknown
Type Detail: None
Speed: Unknown
Manufacturer: [Empty]
Serial Number: [Empty]
Asset Tag: 9876543210
Part Number: [Empty]
Rank: Unknown
Configured Clock Speed: Unknown
Handle 0x0010, DMI type 17, 34 bytes
Memory Device
Array Handle: 0x000C
Error Information Handle: Not Provided
Total Width: Unknown
Data Width: Unknown
Size: No Module Installed
Form Factor: DIMM
Set: None
Locator: ChannelB-DIMM0
Bank Locator: BANK 2
Type: Unknown
Type Detail: None
Speed: Unknown
Manufacturer: [Empty]
Serial Number: [Empty]
Asset Tag: 9876543210
Part Number: [Empty]
Rank: Unknown
Configured Clock Speed: Unknown
Handle 0x0011, DMI type 17, 34 bytes
Memory Device
Array Handle: 0x000C
Error Information Handle: Not Provided
Total Width: Unknown
Data Width: Unknown
Size: No Module Installed
Form Factor: DIMM
Set: None
Locator: ChannelB-DIMM1
Bank Locator: BANK 3
Type: Unknown
Type Detail: None
Speed: Unknown
Manufacturer: [Empty]
Serial Number: [Empty]
Asset Tag: 9876543210
Part Number: [Empty]
Rank: Unknown
Configured Clock Speed: Unknown
sudo lshw命令：
description: Computer
width: 64 bits
capabilities: smbios-2.7 vsyscall32
*-core
description: Motherboard
physical id: 0
*-memory
description: System memory
physical id: 0
size: 3835MiB
*-cpu
product: Intel(R) Core(TM) i7-4510U CPU @ 2.00GHz
vendor: Intel Corp.
physical id: 1
bus info: cpu@0
size: 2687MHz
capacity: 3100MHz
width: 64 bits
capabilities: fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp x86-64 constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid sse4_1 sse4_2 movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm epb tpr_shadow vnmi flexpriority ept vpid fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid xsaveopt dtherm ida arat pln pts cpufreq
*-pci
description: Host bridge
product: Haswell-ULT DRAM Controller
vendor: Intel Corporation
physical id: 100
bus info: pci@0000:00:00.0
version: 0b
width: 32 bits
clock: 33MHz
configuration: driver=hsw_uncore
resources: irq:0
*-display
description: VGA compatible controller
product: Haswell-ULT Integrated Graphics Controller
vendor: Intel Corporation
physical id: 2
bus info: pci@0000:00:02.0
version: 0b
width: 64 bits
clock: 33MHz
capabilities: msi pm vga_controller bus_master cap_list rom
configuration: driver=i915 latency=0
resources: irq:48 memory:f7400000-f77fffff memory:d0000000-dfffffff ioport:f000(size=64)
*-multimedia:0
description: Audio device
product: Haswell-ULT HD Audio Controller
vendor: Intel Corporation
physical id: 3
bus info: pci@0000:00:03.0
version: 0b
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress bus_master cap_list
configuration: driver=snd_hda_intel latency=0
resources: irq:51 memory:f7a1c000-f7a1ffff
*-generic:0
description: Signal processing controller
product: Intel Corporation
vendor: Intel Corporation
physical id: 4
bus info: pci@0000:00:04.0
version: 0b
width: 64 bits
clock: 33MHz
capabilities: msi pm bus_master cap_list
configuration: driver=proc_thermal latency=0
resources: irq:16 memory:f7a10000-f7a17fff
*-usb
description: USB controller
product: 8 Series USB xHCI HC
vendor: Intel Corporation
physical id: 14
bus info: pci@0000:00:14.0
version: 04
width: 64 bits
clock: 33MHz
capabilities: pm msi xhci bus_master cap_list
configuration: driver=xhci_hcd latency=0
resources: irq:44 memory:f7a00000-f7a0ffff
*-usbhost:0
product: xHCI Host Controller
vendor: Linux 4.4.0-21-generic xhci-hcd
physical id: 0
bus info: usb@2
logical name: usb2
version: 4.04
capabilities: usb-3.00
configuration: driver=hub slots=4 speed=5000Mbit/s
*-usbhost:1
product: xHCI Host Controller
vendor: Linux 4.4.0-21-generic xhci-hcd
physical id: 1
bus info: usb@1
logical name: usb1
version: 4.04
capabilities: usb-2.00
configuration: driver=hub slots=9 speed=480Mbit/s
*-usb:0
description: Mouse
product: USB Gaming Mouse
physical id: 1
bus info: usb@1:1
version: 0.11
capabilities: usb-1.10
configuration: driver=usbhid maxpower=100mA speed=12Mbit/s
*-usb:1
description: Video
product: USB Camera
vendor: 04081-00052400E9E8W6
physical id: 6
bus info: usb@1:6
version: 0.02
serial: 200901010001
capabilities: usb-2.00
configuration: driver=uvcvideo maxpower=500mA speed=480Mbit/s
*-communication
description: Communication controller
product: 8 Series HECI #0
vendor: Intel Corporation
physical id: 16
bus info: pci@0000:00:16.0
version: 04
width: 64 bits
clock: 33MHz
capabilities: pm msi bus_master cap_list
configuration: driver=mei_me latency=0
resources: irq:49 memory:f7a24000-f7a2401f
*-multimedia:1
description: Audio device
product: 8 Series HD Audio Controller
vendor: Intel Corporation
physical id: 1b
bus info: pci@0000:00:1b.0
version: 04
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress bus_master cap_list
configuration: driver=snd_hda_intel latency=0
resources: irq:50 memory:f7a18000-f7a1bfff
*-pci:0
description: PCI bridge
product: 8 Series PCI Express Root Port 1
vendor: Intel Corporation
physical id: 1c
bus info: pci@0000:00:1c.0
version: e4
width: 32 bits
clock: 33MHz
capabilities: pci pciexpress msi pm normal_decode bus_master cap_list
configuration: driver=pcieport
resources: irq:40
*-pci:1
description: PCI bridge
product: 8 Series PCI Express Root Port 3
vendor: Intel Corporation
physical id: 1c.2
bus info: pci@0000:00:1c.2
version: e4
width: 32 bits
clock: 33MHz
capabilities: pci pciexpress msi pm normal_decode bus_master cap_list
configuration: driver=pcieport
resources: irq:41 ioport:e000(size=4096) memory:f7900000-f79fffff
*-generic
description: Unassigned class
product: Realtek Semiconductor Co., Ltd.
vendor: Realtek Semiconductor Co., Ltd.
physical id: 0
bus info: pci@0000:02:00.0
version: 01
width: 32 bits
clock: 33MHz
capabilities: pm msi pciexpress msix vpd bus_master cap_list rom
configuration: driver=rtsx_pci latency=0
resources: irq:45 memory:f7915000-f7915fff memory:f7900000-f790ffff
*-network
description: Ethernet interface
product: RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller
vendor: Realtek Semiconductor Co., Ltd.
physical id: 0.1
bus info: pci@0000:02:00.1
logical name: enp2s0f1
version: 12
serial: ac:9e:17:9c:2b:22
size: 1Gbit/s
capacity: 1Gbit/s
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress msix vpd bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation
configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=full firmware=rtl8411-2_0.0.1 07/08/13 ip=192.168.0.100 latency=0 link=yes multicast=yes port=MII speed=1Gbit/s
resources: irq:47 ioport:e000(size=256) memory:f7914000-f7914fff memory:f7910000-f7913fff
*-pci:2
description: PCI bridge
product: 8 Series PCI Express Root Port 4
vendor: Intel Corporation
physical id: 1c.3
bus info: pci@0000:00:1c.3
version: e4
width: 32 bits
clock: 33MHz
capabilities: pci pciexpress msi pm normal_decode bus_master cap_list
configuration: driver=pcieport
resources: irq:42 memory:f7800000-f78fffff
*-network
description: Wireless interface
product: QCA9565 / AR9565 Wireless Network Adapter
vendor: Qualcomm Atheros
physical id: 0
bus info: pci@0000:03:00.0
logical name: wlp3s0
version: 01
serial: 40:e2:30:58:5c:e7
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress bus_master cap_list rom ethernet physical wireless
configuration: broadcast=yes driver=ath9k driverversion=4.4.0-21-generic firmware=N/A latency=0 link=no multicast=yes wireless=IEEE 802.11bgn
resources: irq:19 memory:f7800000-f787ffff memory:f7880000-f788ffff
*-pci:3
description: PCI bridge
product: 8 Series PCI Express Root Port 5
vendor: Intel Corporation
physical id: 1c.4
bus info: pci@0000:00:1c.4
version: e4
width: 32 bits
clock: 33MHz
capabilities: pci pciexpress msi pm normal_decode bus_master cap_list
configuration: driver=pcieport
resources: irq:43 ioport:d000(size=4096) memory:f6000000-f70fffff ioport:e0000000(size=301989888)
*-display
description: 3D controller
product: GM107M [GeForce GTX 850M]
vendor: NVIDIA Corporation
physical id: 0
bus info: pci@0000:04:00.0
version: a2
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress bus_master cap_list rom
configuration: driver=nvidia latency=0
resources: irq:52 memory:f6000000-f6ffffff memory:e0000000-efffffff memory:f0000000-f1ffffff ioport:d000(size=128) memory:f7000000-f707ffff
*-isa
description: ISA bridge
product: 8 Series LPC Controller
vendor: Intel Corporation
physical id: 1f
bus info: pci@0000:00:1f.0
version: 04
width: 32 bits
clock: 33MHz
capabilities: isa bus_master cap_list
configuration: driver=lpc_ich latency=0
resources: irq:0
*-storage
description: SATA controller
product: 8 Series SATA Controller 1 [AHCI mode]
vendor: Intel Corporation
physical id: 1f.2
bus info: pci@0000:00:1f.2
version: 04
width: 32 bits
clock: 66MHz
capabilities: storage msi pm ahci_1.0 bus_master cap_list
configuration: driver=ahci latency=0
resources: irq:46 ioport:f0b0(size=8) ioport:f0a0(size=4) ioport:f090(size=8) ioport:f080(size=4) ioport:f060(size=32) memory:f7a22000-f7a227ff
*-serial UNCLAIMED
description: SMBus
product: 8 Series SMBus Controller
vendor: Intel Corporation
physical id: 1f.3
bus info: pci@0000:00:1f.3
version: 04
width: 64 bits
clock: 33MHz
configuration: latency=0
resources: memory:f7a21000-f7a210ff ioport:f040(size=32)
*-generic:1 UNCLAIMED
description: Signal processing controller
product: 8 Series Thermal
vendor: Intel Corporation
physical id: 1f.6
bus info: pci@0000:00:1f.6
version: 04
width: 64 bits
clock: 33MHz
capabilities: pm msi bus_master cap_list
configuration: latency=0
resources: memory:f7a20000-f7a20fff
*-scsi:0
physical id: 2
logical name: scsi0
capabilities: emulated
*-disk
description: ATA Disk
product: Samsung SSD 850
physical id: 0.0.0
bus info: scsi@0:0.0.0
logical name: /dev/sda
version: 1B6Q
serial: S21JNXAG905520Y
size: 465GiB (500GB)
capabilities: partitioned partitioned:dos
configuration: ansiversion=5 logicalsectorsize=512 sectorsize=512 signature=09136279
*-volume:0
description: EXT4 volume
vendor: Linux
physical id: 1
bus info: scsi@0:0.0.0,1
logical name: /dev/sda1
logical name: /
version: 1.0
serial: 6939f803-affa-46dc-9d1a-aac12c594658
size: 419GiB
capacity: 419GiB
capabilities: primary journaled extended_attributes large_files huge_files dir_nlink extents ext4 ext2 initialized
configuration: created=2016-04-21 17:58:45 filesystem=ext4 lastmountpoint=/ modified=2016-04-28 18:33:11 mount.fstype=ext4 mount.options=rw,relatime,errors=remount-ro,data=ordered mounted=2016-04-28 18:26:42 state=mounted
*-volume:1
description: Windows NTFS volume
physical id: 2
bus info: scsi@0:0.0.0,2
logical name: /dev/sda2
version: 3.1
serial: 620a-5ce0
size: 498MiB
capacity: 500MiB
capabilities: primary bootable ntfs initialized
configuration: clustersize=4096 created=2016-04-22 09:20:17 filesystem=ntfs label=System Reserved modified_by_chkdsk=true mounted_on_nt4=true resize_log_file=true state=dirty upgrade_on_mount=true
*-volume:2
description: Windows NTFS volume
physical id: 3
bus info: scsi@0:0.0.0,3
logical name: /dev/sda3
version: 3.1
serial: 38cb1e54-8a86-774e-984d-0077359ae116
size: 46GiB
capacity: 46GiB
capabilities: primary ntfs initialized
configuration: clustersize=4096 created=2016-04-22 09:20:20 filesystem=ntfs state=clean
*-scsi:1
physical id: 3
logical name: scsi1
capabilities: emulated
*-cdrom
description: DVD-RAM writer
product: CDDVDW SU-228FB
vendor: TSSTcorp
physical id: 0.0.0
bus info: scsi@1:0.0.0
logical name: /dev/cdrom
logical name: /dev/cdrw
logical name: /dev/dvd
logical name: /dev/dvdrw
logical name: /dev/sr0
version: AS00
capabilities: removable audio cd-r cd-rw dvd dvd-r dvd-ram
configuration: ansiversion=5 status=nodisc
*-scsi:2
physical id: 4
logical name: scsi2
capabilities: emulated
*-disk
description: ATA Disk
product: SanDisk SSD U100
physical id: 0.0.0
bus info: scsi@2:0.0.0
logical name: /dev/sdb
version: 6.02
serial: 132328400701
size: 22GiB (24GB)
configuration: ansiversion=5 logicalsectorsize=512 sectorsize=512 signature=9ae5d9db
free -m命令：
total used free shared buff/cache available
Mem: 3835 1806 948 25 1080 1924
Swap: 0 0 0