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I was thinking about upgrading my laptop's RAM. It currently has a 4096 MB module and a 2048 MB module, which I thought I could replace by an 8 GB module:

[root@...] # dmidecode -t 17
# dmidecode 2.12
SMBIOS 2.6 present.

Handle 0x001E, DMI type 17, 28 bytes
Memory Device
    Array Handle: 0x001D
    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: 1333 MHz
    Manufacturer: Samsung
    Serial Number: 946CAE2D
    Asset Tag: 9876543210
    Part Number: M471B5273CH0-CH9  
    Rank: Unknown

Handle 0x0020, DMI type 17, 28 bytes
Memory Device
    Array Handle: 0x001D
    Error Information Handle: Not Provided
    Total Width: 64 bits
    Data Width: 64 bits
    Size: 2048 MB
    Form Factor: SODIMM
    Set: None
    Locator: ChannelB-DIMM0
    Bank Locator: BANK 2
    Type: DDR3
    Type Detail: Synchronous
    Speed: 1333 MHz
    Manufacturer: Samsung
    Serial Number: C18B2141
    Asset Tag: 9876543210
    Part Number: M471B5773DH0-CH9  
    Rank: Unknown

But then I looked at the Physical Memory Array and discovered that, apparently, the maximum RAM capacity is 8 GB:

[root@...]# dmidecode -t 16
# dmidecode 2.12
SMBIOS 2.6 present.

Handle 0x001D, DMI type 16, 15 bytes
Physical Memory Array
    Location: System Board Or Motherboard
    Use: System Memory
    Error Correction Type: None
    Maximum Capacity: 8 GB
    Error Information Handle: Not Provided
    Number Of Devices: 2

Now, searching on the internet it seems that some people are claiming to be using 2x8 GB modules with the same laptop model, BIOS and processor even when the manufacturer still says that this is not supported. If you read through that thread you'll find different users confirming that doing a RAM upgrade worked for them regardless of the manufacturer's official claim.

My question is: is this possible? Which are the implications of the dmidecode -t 16 output? Is the Maximum Capacity an arbitrary value that can be set/faked by the manufacturer to "force" you to upgrade your whole laptop instead of just upgrading your RAM? Or is it a real physical limitation that would make an upgrade impossible when inserting more than the 8 GB Maximum Capacity?

Marcelo
  • 177
Peque
  • 1,079

2 Answers2

4

Yes, it is and I can refer to at least one case:

Macs are good examples of machines that do support more memory than the manufacturer (Apple) say their limit is.

I have had a MacMini 2011 w/ Linux installed on it in which dmidecode (as well as the Manufacturer specs) claim to be limited to 8GB but with 16GB installed and running fine for years.

One thing to consider though is that although (for newer Intel processors*) the real limiter is in fact the processor, the system may have been designed and tested for smaller memory amounts. You should take in consideration factors like power consumption, heat dissipation, etc. So, upgrading to more memory than the manufacturer specs may be pushing one of these factors above the design, which in theory can void your warranty or shorten the device's lifetime.

*Why is the limiter the processor and not the system? Because since the core i[3|5|7] processor generations, the memory controller is now embedded in the processor chip itself, which means that each memory pin is directly connected to a processor pin.

Marcelo
  • 177
0

The information in the DMI table is provided by the manufacturer, so yes, they can put whatever they want in there. It would be very odd though, for them to claim less memory support than the platform actually does handle.

I believe you are misinterpreting what it says though. I believe it is saying the limit is 8 GB per SODIMM, so you can use 2 x 8G to get a total of 16.

psusi
  • 8,122