I have a problem which may be Linux related or may be hardware. My old machine has an ASRock G31M-S motherboard, Q6600 CPU. Bios is as up to date as one could expect from so venerable device and sees 8Gb memory (2 x 4Gb)

Lshw -short -C memory returns:

H/W path Device Class Description
==============================================================
/0/0 memory 64KiB BIOS
/0/4/5 memory 128KiB L1 cache
/0/4/6 memory 8MiB L2 cache
/0/e memory 8GiB System Memory
/0/e/0 memory 4GiB DIMM SDRAM Synchronous
/0/e/1 memory 4GiB DIMM SDRAM Synchronous

But free -g returns:

total used free shared buff/cache available
Mem: 3 1 0 0 1 1
Swap: 42 0 42

So although I have 8Gb physical memory on-board and the MoBo can handle 8 Gb, Mint 19 (64bit) is only seeing 3 Gb. Any clues as to why this should be ? I suspect this may have been asked before but my Google-Fu seems weak today.

While at least some of the memory (maybe just 200-300MB depending on your mobo) will not be available to the operating system, because it used by the machine itself, there should be more than 3GiB available to Linux if you have 8GiB of RAM.

Have you tried putting some known good memory in it, or tried putting that same memory in another machine to see if you have the same problem?

Does the BIOS see the 8GiB of RAM?

Have you tried putting some known good memory in it, or tried putting that same memory in another machine to see if you have the same problem?

Does the BIOS see the 8GiB of RAM?[/QUOTE]


BIOS sees 2x4gb ram. The memory modules came out of a known working machine. I have no spare 4 Gb modules but I will test the board with 2 x 2Gb modules & see what I get.

Strange. cat /proc/meminfo gives:

....8 Gb modules............................4 Gb modules
MemTotal: 3265720 kB............MemTotal: 3265720 kB
MemFree: 181748 kB............MemFree: 2028588 kB
MemAvailable: 1503348 kB............MemAvailable: 2438332 kB
Buffers: 45172 kB............Buffers: 83124 kB
Cached: 1479112 kB............Cached: 491196 kB
SwapCached: 0 kB............SwapCached: 0 kB
Active: 1430828 kB............Active: 637812 kB
Inactive: 1413736 kB............Inactive: 425472 kB

Try entering the BIOS setup and enabling the "Memory Remap Feature" option.

https://www.asrock.com/support/faq.asp?id=238

You are absolutely right. I found that last night - the blurb is a bit confusing.

Great. If that worked, you can mark the thread as "Solved" using "Thread Tools" at the top of the thread.