Take the 2-minute tour ×
Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

I have a System76 wilp9 machine running Ubuntu 14.04 which came with 32GB of RAM installed. When I rebooted it today, it displayed a warning that the memory decreased, and now both the bios and linux will only detect 16GB of RAM at a time.

I've tried re-seating and rearranging the DIMMs, and at a glance it doesn't appear to be an issue with any of the slots or DIMMs (i.e. if I install just 2 DIMMs at a time, I can get the 16GB of ram to show up using both possible pairs of slots, and swapping the pairs of DIMMs in the same slots also works, so it doesn't seem like a hardware/connection problem). Normally I would run a memtest to verify the memory is OK, but memtest only shows 16GB of RAM as well...

The really odd thing is that all of the info about the missing RAM (except size) shows up in lshw even though it says "[empty]" in the description, which is different than when the slot is actually empty. For example, here's the output of lshw -C memory when I've installed DIMMs into 3 slots and left 1 empty:

sudo lshw -C memory
  *-firmware              
       description: BIOS
       vendor: Intel Corp.
       physical id: 0
       version: KCH7710H.86A.0103.2012.1029.1732
       date: 10/29/2012
       size: 64KiB
       capacity: 8128KiB
       capabilities: pci upgrade shadowing cdboot bootselect socketedrom edd int13floppy1200 int13floppy720 int13floppy2880 int5printscreen int9keyboard int14serial int17printer acpi usb biosbootspecification uefi
  *-cache:0
       description: L1 cache
       physical id: 4
       slot: CPU Internal L1
       size: 256KiB
       capacity: 256KiB
       capabilities: internal write-through data
  *-cache:1
       description: L2 cache
       physical id: 5
       slot: CPU Internal L2
       size: 1MiB
       capacity: 1MiB
       capabilities: internal write-through unified
  *-cache:2
       description: L3 cache
       physical id: 6
       slot: CPU Internal L3
       size: 8MiB
       capacity: 8MiB
       capabilities: internal write-back unified
  *-memory
       description: System Memory
       physical id: 7
       slot: System board or motherboard
       size: 16GiB
     *-bank:0
          description: DIMM DDR3 Synchronous 1600 MHz (0.6 ns) [empty]
          product: BLS8G3D1609DS1S00.
          vendor: 859B
          physical id: 0
          serial: A406D807
          slot: DIMM3
          width: 64 bits
          clock: 1600MHz (0.6ns)
     *-bank:1
          description: DIMM DDR3 Synchronous 1600 MHz (0.6 ns)
          product: BLS8G3D1609DS1S00.
          vendor: 859B
          physical id: 1
          serial: A406D817
          slot: DIMM1
          size: 8GiB
          width: 64 bits
          clock: 1600MHz (0.6ns)
     *-bank:2
          description: DIMM [empty]
          product: [Empty]
          vendor: [Empty]
          physical id: 2
          serial: [Empty]
          slot: DIMM4
     *-bank:3
          description: DIMM DDR3 Synchronous 1600 MHz (0.6 ns)
          product: BLS8G3D1609DS1S00.
          vendor: 859B
          physical id: 3
          serial: A406D80D
          slot: DIMM2
          size: 8GiB
          width: 64 bits
          clock: 1600MHz (0.6ns)

Finally, starting today the machine has just completely powered off out of nowhere twice (including once while drafting this question). I'm not sure how to diagnose that issue, as I don't see anything obvious/useful in kern.log or in the bios event log.

Potentially unrelated, but I've also sometimes seen a message "ME FW UPDATE FAILED" when booting. I'm not sure what it means, but it sounded like it might be related to this mess, but I have no clue.

Any ideas? This machine was working just fine up until this morning when I rebooted it.


Update: Michael Frank asked what happens if I use the other 2 slots. As mentioned above, they function just fine when the other 2 DIMMs aren't installed. To verify, I moved the 2 DIMMs that were active in the example above (serials A406D817 and A406D80D) to the 2 slots that weren't being used in the example above (banks 0 and 2) and rebooted and re-ran lshw, which shows that banks 0 and 2 also function just fine:

  *-memory
       description: System Memory
       physical id: 7
       slot: System board or motherboard
       size: 16GiB
     *-bank:0
          description: DIMM DDR3 Synchronous 1600 MHz (0.6 ns)
          product: BLS8G3D1609DS1S00.
          vendor: 859B
          physical id: 0
          serial: A406D817
          slot: DIMM3
          size: 8GiB
          width: 64 bits
          clock: 1600MHz (0.6ns)
     *-bank:1
          description: DIMM [empty]
          product: [Empty]
          vendor: [Empty]
          physical id: 1
          serial: [Empty]
          slot: DIMM1
     *-bank:2
          description: DIMM DDR3 Synchronous 1600 MHz (0.6 ns)
          product: BLS8G3D1609DS1S00.
          vendor: 859B
          physical id: 2
          serial: A406D80D
          slot: DIMM4
          size: 8GiB
          width: 64 bits
          clock: 1600MHz (0.6ns)
     *-bank:3
          description: DIMM [empty]
          product: [Empty]
          vendor: [Empty]
          physical id: 3
          serial: [Empty]
          slot: DIMM2

For completeness, I also tried installing the other two DIMMs into those same banks (0 and 2), which also work just fine:

  *-memory
       description: System Memory
       physical id: 7
       slot: System board or motherboard
       size: 16GiB
     *-bank:0
          description: DIMM DDR3 Synchronous 1600 MHz (0.6 ns)
          product: BLS8G3D1609DS1S00.
          vendor: 859B
          physical id: 0
          serial: A406D807
          slot: DIMM3
          size: 8GiB
          width: 64 bits
          clock: 1600MHz (0.6ns)
     *-bank:1
          description: DIMM [empty]
          product: [Empty]
          vendor: [Empty]
          physical id: 1
          serial: [Empty]
          slot: DIMM1
     *-bank:2
          description: DIMM DDR3 Synchronous 1600 MHz (0.6 ns)
          product: BLS8G3D1609DS1S00.
          vendor: 859B
          physical id: 2
          serial: A406D80C
          slot: DIMM4
          size: 8GiB
          width: 64 bits
          clock: 1600MHz (0.6ns)
     *-bank:3
          description: DIMM [empty]
          product: [Empty]
          vendor: [Empty]
          physical id: 3
          serial: [Empty]
          slot: DIMM2
share|improve this question
    
I would update the firmware on your BIOS and/or reset BIOS because the hardware clearly isn't being detected. –  Ramhound May 27 at 22:34
    
You mentioned swapping the RAM in pairs in the same slots, do the other slots work? Try the RAM in banks 0 and 2. –  Michael Frank May 27 at 22:50
    
Also start removing RAM and try to isolate the problematic stick –  Mike K May 27 at 23:43
    
@Ramhound I can certainly update the BIOS, but I'd first like to understand the issue, since the symptoms don't suggest a BIOS issue to me - it started after a simple reboot (i.e. I haven't touched anything in BIOS or updated the BIOS recently). If nothing else comes up, I will go ahead and try that though, as it looks like there have been several updates to my BIOS version: downloadmirror.intel.com/22372/eng/KC_0106_ReleaseNotes.pdf –  scottbez1 May 27 at 23:47
    
@MichaelFrank The other slots and other DIMMs appear to work just fine. I've updated the question with the results of lshw after trying banks 0 and 2 as you suggested, and also swapping in the other 2 DIMMs that weren't being used in the original configuration (serials A406D807 and A406D80C) - so all 4 slots and all 4 DIMMs seem to work just fine when tested in sets of 2. –  scottbez1 May 27 at 23:51

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.