I've installed 8GB of RAM (2x4GB) in my computer. Before I have only 4GB (1x4GB), and I've installed the new cards one where the oldest was and the other in the other slot of the same type. But if I check my Ubuntu's details or htop, it only shows 4GB (3'8GB). My motherboard is Asus P7H55-M. In windows it detects 8GB but it says that it only can use 4GB, don't know why. This are my outputs. (there are in spanish)
free -h:
total usado libre compart. búffers
almac.
Mem: 3,8G 2,2G 1,6G 18M 119M 869M
-/+ buffers/cache: 1,2G 2,6G
Intercambio: 4,5G 0B 4,5G
sudo dmidecode --type memory:
SMBIOS 2.6 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:
Other
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: Unknown
Type: DIMM SDRAM
Installed Size: 4096 MB (Double-bank Connection)
Enabled Size: 4096 MB (Double-bank Connection)
Error Status: OK
Handle 0x000A, DMI type 6, 12 bytes
Memory Module Information
Socket Designation: DIMM1
Bank Connections: 2 3
Current Speed: Unknown
Type: DIMM SDRAM
Installed Size: Not Installed
Enabled Size: Not Installed
Error Status: OK
Handle 0x000B, DMI type 6, 12 bytes
Memory Module Information
Socket Designation: DIMM2
Bank Connections: 4 5
Current Speed: Unknown
Type: DIMM SDRAM
Installed Size: 4096 MB (Double-bank Connection)
Enabled Size: 4096 MB (Double-bank Connection)
Error Status: OK
Handle 0x000C, DMI type 6, 12 bytes
Memory Module Information
Socket Designation: DIMM3
Bank Connections: 6 7
Current Speed: Unknown
Type: DIMM SDRAM
Installed Size: Not Installed
Enabled Size: Not Installed
Error Status: OK
Handle 0x0036, DMI type 16, 15 bytes
Physical Memory Array
Location: System Board Or Motherboard
Use: System Memory
Error Correction Type: None
Maximum Capacity: 16 GB
Error Information Handle: Not Provided
Number Of Devices: 4
Handle 0x0038, DMI type 17, 28 bytes
Memory Device
Array Handle: 0x0036
Error Information Handle: Not Provided
Total Width: 64 bits
Data Width: 64 bits
Size: 4096 MB
Form Factor: DIMM
Set: None
Locator: DIMM0
Bank Locator: BANK0
Type: DDR
Type Detail: Synchronous
Speed: 1333 MHz
Manufacturer: Manufacturer0
Serial Number: SerNum0
Asset Tag: AssetTagNum0
Part Number: PartNum0
Rank: Unknown
Handle 0x003A, DMI type 17, 28 bytes
Memory Device
Array Handle: 0x0036
Error Information Handle: Not Provided
Total Width: Unknown
Data Width: Unknown
Size: No Module Installed
Form Factor: DIMM
Set: None
Locator: DIMM1
Bank Locator: BANK1
Type: Unknown
Type Detail: Unknown
Speed: Unknown
Manufacturer: Manufacturer1
Serial Number: SerNum1
Asset Tag: AssetTagNum1
Part Number: PartNum1
Rank: Unknown
Handle 0x003C, DMI type 17, 28 bytes
Memory Device
Array Handle: 0x0036
Error Information Handle: Not Provided
Total Width: 64 bits
Data Width: 64 bits
Size: 4096 MB
Form Factor: DIMM
Set: None
Locator: DIMM2
Bank Locator: BANK2
Type: DDR
Type Detail: Synchronous
Speed: 1333 MHz
Manufacturer: Manufacturer2
Serial Number: SerNum2
Asset Tag: AssetTagNum2
Part Number: PartNum2
Rank: Unknown
Handle 0x003E, DMI type 17, 28 bytes
Memory Device
Array Handle: 0x0036
Error Information Handle: Not Provided
Total Width: Unknown
Data Width: Unknown
Size: No Module Installed
Form Factor: DIMM
Set: None
Locator: DIMM3
Bank Locator: BANK3
Type: Unknown
Type Detail: Unknown
Speed: Unknown
Manufacturer: Manufacturer3
Serial Number: SerNum3
Asset Tag: AssetTagNum3
Part Number: PartNum3
Rank: Unknown
With dmicoded it shows that there are two RAMs of 4GB.
And, obviously I'm using a 64bits kernel:
Linux m0skva 3.13.0-53-generic #89-Ubuntu SMP Wed May 20 10:34:39 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
The BIOS memory remaping is enabled. I don't know what more to do.