My laptop is Thinkpad T400, and running 64 bit Ubuntu 14.04. I wonder if there is no limit of the RAM size that I can use in my laptop?

Now I am running Windows 8.1 in VirtualBox, which takes 2GB RAM, and if I open 80 Chrome tabs, My RAM (8GB, which is two 4GB RAM cards occupying two slots in the laptop, I am not sure if there are extra slots) will be fully used, and my swap (16GB) will be half full, and the speed is slow because of constant swapping.

I am thinking about upgrade my RAM to a bigger size (maybe 32GB or more). But not sure if there is some limitations on the RAM size, how many RAM cards I could buy and insert into the laptop, and other aspects that I should be aware of. So I appreciate your reply!

  • The amusing thing is that both kazoni and I have found official documentation on your laptop. Could you please confirm which one applies? At any rate, the maximum amount is either 4GB or 8GB, which is quite typical for a laptop these days. – MariusMatutiae Jun 15 '15 at 16:26
  • I can only confirm I am using 8GB RAM. @Mar – Tim Jun 15 '15 at 16:27
  • I am running other programs, and it is not simple to open the hood. @Ram – Tim Jun 15 '15 at 16:29

No pc has an infinitely expandable amount of RAM, there is always a limit. This is especially true for the cramped laptops.

In your case, the official documentation by Lenovo states:

Supports up to 4GB maximum memory

There are several commands within Linux that allow checking the size of available memory. Among them:

  sudo dmidecode --type memory  #obsolete, I believe
  cat /proc/meminfo
  free -m
  vmstat -s 
  sudo lshw -C memory

and probably a few more, which I cannot even remember now. You might use one of these to double check the amount of memory you claim to have, because it seems to be incompatible with the Official documentation on your laptop.

  • There are 2 S-DIMM slots each of which can contain up to 4 GB, which is 8 GB in total. – DavidPostill Jun 15 '15 at 16:24

No, 8GB is the maximum amount of RAM your laptop supports. Source


Is there a limit to the RAM that I can use in my laptop?

You already have the maximum of 8 GB memory

There are 2 S-DIMM slots each of which can contain up to 4 GB, which is 8 GB in total.


Up to 8GB of PC2-8500 1066 mHz DDR3

Source Thinkpad T400 and T500 Specifications


  • PC3-8500 Non-Parity (NP) Double Data Rate Three (DDR3) Technology
  • Two SO-DIMM Slots
    • The use of 1067 MHz SO DIMM memory is recommended for this system.
  • 512 MB, 1 GB, 2GB, or 4GB memory
  • Supports up to 4GB maximum memory

Note: Only 64-bit operating systems support more than 3GB of system memory

Source Detailed specifications - ThinkPad R400, T400

The T400 support max 8gb of RAM, but some info from Lenovo is old and outdated because at some point there was no 4gb memory modules available so even if the chipset did support 8gb of RAM there was nowhere you could actually buy the 4gb modules. Now the 4gb modules been available for some time and it should work fine.

I have added 8gb of RAM for the T400 and it's working fine. I bought the RAM from Lenovo.

Part no: 55Y3708

Spec: SO DIMM 204-pins - DDR3 - 1066 MHz / PC3-8500 - 1.5 V, Non-EEC

Source T400 - 8GB Maximum RAM / Memory Issue!

  • What laptops can support more RAM? – Tim Jun 15 '15 at 16:24
  • That is off-topic for Super User (too broad) – DavidPostill Jun 15 '15 at 16:25
  • Are most recent laptops support more RAM? – Tim Jun 15 '15 at 16:26
  • No, I read the same sentence as no more than 4GB total, not per slot. – MariusMatutiae Jun 15 '15 at 16:27
  • @MariusMatutiae Specifications say otherwise. – Ramhound Jun 15 '15 at 16:29

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