DDR3 4x4 seen as 8GiB not 16Gib

**Torxbit** · May 4th, 2017

I have an MSI 970A-G45 (MS-7693) motherboard. In it are 4 DIMMS of 4G memory. All are Corsair 1333Mhz 9-9-9-24 modules. The BIOS sees 16G, memtest sees all 4 DIMMs but only sees 8G of memory. Strangly enough it thinks it is in XMP mode. The motherboard is an AMD board, not Intell.

Linux <redacted> 4.4.0-75-generic #96-Ubuntu SMP Thu Apr 20 09:56:33 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

lshw sees 16G
*-memory
description: System Memory
physical id: 27
slot: System board or motherboard
size: 16GiB
*-bank:0
description: DIMM DDR3 Synchronous 667 MHz (1.5 ns)
product: Array1_PartNumber0
vendor: A1_Manufacturer0
physical id: 0
serial: A1_SerNum0
slot: A1_DIMM0
size: 4GiB
width: 64 bits
clock: 667MHz (1.5ns)
*-bank:1
description: DIMM DDR3 Synchronous 667 MHz (1.5 ns)
product: Array1_PartNumber1
vendor: A1_Manufacturer1
physical id: 1
serial: A1_SerNum1
slot: A1_DIMM1
size: 4GiB
width: 64 bits
clock: 667MHz (1.5ns)
*-bank:2
description: DIMM DDR3 Synchronous 667 MHz (1.5 ns)
product: Array1_PartNumber2
vendor: A1_Manufacturer2
physical id: 2
serial: A1_SerNum2
slot: A1_DIMM2
size: 4GiB
width: 64 bits
clock: 667MHz (1.5ns)
*-bank:3
description: DIMM DDR3 Synchronous 667 MHz (1.5 ns)
product: Array1_PartNumber3
vendor: A1_Manufacturer3
physical id: 3
serial: A1_SerNum3
slot: A1_DIMM3
size: 4GiB
width: 64 bits
clock: 667MHz (1.5ns)

free sees 8
total used free shared buff/cache available
Mem: 7953 608 6909 17 435 7059
Swap: 16352 0 16352

And /proc/meminfo sees 8G
MemTotal: 8144764 kB
MemFree: 7075888 kB
MemAvailable: 7228616 kB
Buffers: 39852 kB
Cached: 328452 kB
SwapCached: 36 kB

I have gone over the BIOS settings, reset the CMOS and even tried manual timings per above. I have even removed the DIMMs and cleaned the contacts. Still only 8G is seen. dmesg has no memory errors.

Has anyone ran across this before?

**Bucky Ball** · May 4th, 2017

Is it a new board? It could be the pair of RAM slots. It can happen. Hard to imagine both sticks of RAM are dead. Have you swapped them into the two slots you know are working and the two that are currently in there into the slots that aren't, if you follow me?

Try all four a pair at a time in the two working slots and see what happens.

And yes, I have had two slots die, which is why I mention it.

**Yellow Pasque** · May 5th, 2017

Are you using the latest BIOS? Changelog for 2.7 says something about memory size not identified properly. https://us.msi.com/Motherboard/suppo...html#down-bios

**Torxbit** · May 5th, 2017

Yes, I change the BIOS from the 1.X version to the 2.X version. This added EFI, which I really do not care for. As for switching the memory the board has two matched slots. Ubuntu only recognizes one of the DIMMs from each slot. Each DIMM works independently, and checks out with memtest86+. And even when the option for XMP is disabled in BIOS memtest still thinks it is in XMP configuration.

**Bucky Ball** · May 6th, 2017

Still confused. So each DIMM works independently in both slots when inserted on its own?

**Torxbit** · May 8th, 2017

Yes, but not exactly. The board has dual channel memory. The DIMMs much match and are paired in DIMM1 with DIMM3 and DIMM2 with DIMM4. And if you put in only one DIMM you have to start with DIMM2. But yes, each DIMM tests fine in the slot. But Ubuntu fails to see the second DIMM in the paired slot.