Where did my RAM go?

Support & Help Requests Hardware
#1

Perhaps this should be in hardware forum - so, apologies if if I should have.

i have a couple of laptops i intend to repurpose (Dell Latitudes E5500).

At BIOS they are 4G machines.
Physically inspecting the RAM it's 2 x 2G sticks

Running Mate 19.04
In "About this computer" it is being reported as 1.9GiB
In free -m it's being reported as 1946

Where did my RAM go? Am i misinterpreting something? Running the wrong commands?

These machines are bit slow so finding the extra 2G would be great..

Thanks in advance.

#2

memory sticks could be different type or voltage ... boot with one stick, shutdown, boot with the other stick, find out if one is faulty. DELL E5500 uses DDR2-800, non-ecc, unbuffered, 1.8V if that helps.

#3

thanks for the info - I will try that, but in the Bios its being reported as 4G and this is across 2 machines and 4 different sets of RAM. Memory sticks 'match' (pair to pair) so that lessens some of the possibilities.

I haven't tried running memtest. So that's my next step

I'm also going to live boot off 18.04 (10?) {whatever the LTS was] in case it's something peculiar to 19.04.

More info to follow....

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#4

GNU/Linux makes as much use of the RAM as it can for things like cache, to speed up the system.

So in the free -m command, you'll want to check the "available" column too. The "total" should be around 4096 (4G) if the OS is correctly working with all your RAM, which I suspect it should be if the BIOS reports 4 GiB.

Take a look at this website for more detail on how memory usage works:

https://www.linuxatemyram.com/

#5

Look for this Ram map table by using the "dmesg" command. I usually redirect the output to a file for easy study: dmesg >study.txt

[ 0.000000] e820: BIOS-provided physical RAM map:
[ 0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009fbff] usable
[ 0.000000] BIOS-e820: [mem 0x000000000009fc00-0x000000000009ffff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000000e0000-0x00000000000fffff] reserved
[ 0.000000] BIOS-e820: [mem 0x0000000000100000-0x000000009ffeffff] usable
[ 0.000000] BIOS-e820: [mem 0x000000009fff0000-0x000000009fffefff] ACPI data
[ 0.000000] BIOS-e820: [mem 0x000000009ffff000-0x000000009fffffff] ACPI NVS
[ 0.000000] BIOS-e820: [mem 0x00000000fec00000-0x00000000fec01fff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000fee00000-0x00000000fee00fff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000fff80000-0x00000000ffffffff] reserved

Using the above example, usable ram is from 9FFEFFFF down to 100000 or 2683240447 bytes (2.5 GB).

djb

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#6

thanks for all the suggestions

Managed to spend some time on this yesterday.

After much checking/scratching of head/internet research/running memtest, dmesg, etc, etc I can impart the following weirdness...

On one machine even though bios reported 4G - memtest only reported 2G (as did Ubuntu). After swapping sticks back and forth multiple times I finally managed to obtain 4G by using one stick from each pair. This is despite them ALL being identical Samsung branded 2G sticks.

Have to now try the other machine (with the two remaining sticks) to see what other conclusions I can draw.

#7

Results from 2nd machine are in..

I have 2 sticks of Samsung ram with the same part number that don't play well together

Despite Bios reporting 4G, every thing else only reports 2G.

Solution was to use 2 differing brands of of 2G sticks.. 1 x Samsung + 1 x Kinsgston.

So EITHER of the suspect Samsung sticks with Kingston = 4G
Both of the Samsung sticks together = 2G.

ALL sticks pass memtest OK

Weird.

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#8

Yeah that's amazingly weird.
Did you try swapping one RAM stick between the two machines?

#9

not sure if someone suggested,
try sudo lshw -c memory and look at the two banks info (-bank:0 and -bank:1).

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#10

yes (kind of) each of the 4 sticks reported 2G (both in Bios and mate) when installed separately. This was in one machine only.

I didn't try all 4 in the 2nd machine, as once I had a solution, i just kinda kept on going... (I had wasted enough time on the issue)