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I have an old PC at home with 1.5 GB of RAM and as expected its quite slow.

So I decided to install Ubuntu on a different PC. Intel Quad Core and 4 GB of memory, and a graphic card with dedicated memory. I installed the 64 bit version.

I also notice its much slower that running Windows 7 (that was unexpected) and Ubuntu only seems to recognize 2.9 GB.

Ive been searching this forum, I see chat about bad memory and installing 32 bit version. I've run memtest and no errors there. I've made sure I have 64 bit version installed.

What else can I do?

Follow UP: So after the reply from (MrVaykadji - Thanks :) ) here are the results:

speed@testing:~$ arch 

speed@testing:~$ free -h | awk 'NR>0{arr[$2]}END{for(i in arr) print i}' | grep G 

speed@testing:~$ sudo lshw -class memory | grep GiB  
[sudo] password for speed: 

size: 4GiB 
    size: 2GiB 
    size: 2GiB

It all seems to me to be 64bit system. What now?!

Please... Anyone knows how to fix this?

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With the informations you added, we now know that your system is a 64 bits, that he uses only 3GiB of RAM but sees 4GiB (2x 2GiB) installed on the motherboard. That's a start: the problem is software-related, nothing to do with your hardware apparently. :) – MrVaykadji Feb 25 '14 at 20:19
Hi. I mite add that windows 7 did "see" the full 4GB of RAM before I formated and installed Ubuntu. So... what now? What can I do or change to try and sort this out? Thanks – user2958509 Feb 26 '14 at 0:47
Please, add dmesg output. – Hi-Angel Oct 6 '15 at 4:37

To see what architecture (32bits=x86 or 64bits=x86_64) you have installed :


To see the total RAM (in GB) the software-part of the system detects :

free -h | awk 'NR>0{arr[$2]}END{for(i in arr) print i}' | grep G

To see the total RAM (in GiB) the hardware-part of the system detects :

sudo lshw -class memory | grep GiB -m 1 

To see each RAM slot and what does your system sees installed in each* :

sudo lshw -class memory | grep GiB 

note : GB is gigabyte (1000³ bytes, decimal table) and GiB is gibibyte (1024³ bytes, binary table). It's OK to see exactly how much RAM you have in GiB and it also is OK to see a little less than "real" RAM you have in GB. Just saying.

In this example, I use my own system, which :

  • it has a 64bits (x86_64) architecture.
  • it uses 7,8GB (= 8GiB) of RAM
  • it has 8GiB installed on the motherboard
  • it has 4x 2GiB installed (2GiB per slot)

note: "taille" means "size" in french.

output example

This should help you at first, I'll come back if I think of something else. Hopefully it will be a real answer, this is at most a tip to verify your sayings and what your system sees.

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When you overclock RAM it might not be seen properly.I had to slow down the timings a bit to use all of my RAM. Hope this helps someone overclocking.

Use memtest though when you overclock. You dont want stability issues.

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