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


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)
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    Computer Science 101 - some memory is always reserved for peripherals, including video, keyboard, and mouse/touchpad. +1 – Sergiy Kolodyazhnyy May 8 '15 at 21:46

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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    Disks are marketed this way, but RAM is always manufactured in power-of-two sizes. An "8GB" stick of RAM is always 8GiB. – Tullo_x86 Feb 21 '18 at 4:15

Because that's the actual size of your RAM. They say it's 8GB because it's easier to market.

  • Well It was 2 4Gb modules so each one is 3.85? That is odd. – Todd May 8 '15 at 21:28
  • @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 – Sergiy Kolodyazhnyy May 8 '15 at 21:50
  • @Serg Ok great info, I did not know that – Todd May 8 '15 at 21:52
  • Human understanding = easier to market (and profit). :) – Thiago Zanetti May 8 '15 at 21:53
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    -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). – David Foerster May 9 '15 at 8:49

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