Why does the system report 7.7Gb of total Ram when I installed 8Gb?

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Solution 1

The BIOS will reserve some memory, as will the most primitive level of the kernel, including some for video, perhaps. What is reported to you via system-info (which I don't use) or free -m is what is left.
If you observe the entries in the /var/log/kern.log file from during boot, you will see many having to do with reserving memory and such, and finally, a summary line:

May  3 14:27:20 s15 kernel: [    0.000000] Memory: 15975452K/16472972K available (8029K kernel code, 1240K rwdata, 3736K rodata, 1424K init, 1292K bss, 497520K reserved, 0K cma-reserved)

Solution 2

My system claimed to have 8 GB (gigabyte) of RAM. Ubuntu says it has 7.7 GiB (gibibyte).

7.7 GiB (gibibyte) = 8.26781 GB (gigabyte)

8 Gb (gigabit) = 1 GB (gigabyte)

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Updated on September 18, 2022

Comments

  • Todd
    Todd almost 2 years

    Why does the system report 7.7Gb of total Ram when I installed 8Gb? I'm using 14.04 on a Dell Vostro 2011

  • Todd
    Todd about 9 years
    Well It was 2 4Gb modules so each one is 3.85? That is odd.
  • Sergiy Kolodyazhnyy
    Sergiy Kolodyazhnyy about 9 years
    Computer Science 101 - some memory is always reserved for peripherals, including video, keyboard, and mouse/touchpad. +1
  • Sergiy Kolodyazhnyy
    Sergiy Kolodyazhnyy about 9 years
    @Todd memory is always a power of 2^x. 8GB is what we humans understand , but 2^32 is 4GB (rounded up). Now like Dough mentioned , there's always some memory reserved by the system. Mine is one 4gb stick and 2gb stick, but reported by free -h is 5.6 gb. Has nothing really to do with marketing, just human understanding
  • Todd
    Todd about 9 years
    @Serg Ok great info, I did not know that
  • Thiago Zanetti
    Thiago Zanetti about 9 years
    Human understanding = easier to market (and profit). :)
  • Todd
    Todd about 9 years
    Ok it just seemed an anomaly, not like this is a life or death situ...tx all
  • David Foerster
    David Foerster about 9 years
    -1 That's just plain wrong for DRAM (primary storage). Read the other answer for the correct explanation. Your explanation may work for hard disks and other secondary or tertiary storage, which is marketed with size in gigabytes, while many programs display size in gibibytes, even if they don't say so (though 8 GB ≃ 7.45 GiB).
  • Tullo_x86
    Tullo_x86 over 6 years
    Disks are marketed this way, but RAM is always manufactured in power-of-two sizes. An "8GB" stick of RAM is always 8GiB.
  • wilmol
    wilmol over 2 years
    Interesting - so 1GB RAM is really 1GiB RAM. While 1GB disk is 1GB disk. Also Windows seems to get it wrong, it reports GB when really its showing GiB - my 1TB disk show as 931GB in Windows but as 1TB is Linux.