Usable RAM is not what is should be

[OC-K1NG]

Hi, I've encountered this issue and to be honest, I've run out of ideas and other hardware to test with.

 

My system is running Linux (Ubuntu Studio to be exact) but I don't know if this is a problem with the software as I get the same info when booting to a live USB.

 

The Problem:  I have installed 4 x 4GB DDR3 1600 9-9-9-24 (matching) sticks.  They recognise in the UEFI/BIOS they are detected when running the "sudo lshw | grep -A 8 bank" command in the terminal (output below) however the total memory detected by the OS (or live USB OS) is only 7.5GB.  The problem persists with all amounts of RAM above 8GB, including 2x8GB and 4x8GB all at 1600Mhz but lowering speeds or timing makes no difference. In addition, the 8GB sticks are 1.5v and the 4GB sticks are 1.65v so no mixing of capacities has been done.

• OS - Linux x86-84 (Ubuntu Studio)
• Age of system - Yeah right, old but kept in good condition
• Age of OS installation - 3 Days but happened pre install on Live USB
• CPU - AMD FX 9590 (with watercooler and Thermal Grizzly Kryonaut TIM
• Video Card - AMD HD 7790 1GB
• MotherBoard - Gigabyte GA-990FXA-UD5 Revision 3
• Power Supply - Antec 750w High Current Gamer
• System Manufacturer - None, Custom Build

Below are some commands to illustrate my issue

 

>sudo lshw | grep -A 8 bank

       *-bank:0
            description: DIMM DDR3 Synchronous Unbuffered (Unregistered) 667 MHz (1.5 ns)
            product: 9905403-489.A
            vendor: Kingston
            physical id: 0
            serial: 570DDE08
            slot: Node0_Dimm0
            size: 4GiB
            width: 64 bits
--
       *-bank:1
            description: DIMM DDR3 Synchronous Unbuffered (Unregistered) 667 MHz (1.5 ns)
            product: 9905403-489.A
            vendor: Kingston
            physical id: 1
            serial: 590DE408
            slot: Node0_Dimm1
            size: 4GiB
            width: 64 bits
--
       *-bank:2
            description: DIMM DDR3 Synchronous Unbuffered (Unregistered) 667 MHz (1.5 ns)
            product: 9905403-489.A
            vendor: Kingston
            physical id: 2
            serial: 570DE708
            slot: Node0_Dimm2
            size: 4GiB
            width: 64 bits
--
       *-bank:3
            description: DIMM DDR3 Synchronous Unbuffered (Unregistered) 667 MHz (1.5 ns)
            product: 9905403-489.A
            vendor: Kingston
            physical id: 3
            serial: 480D1213
            slot: Node0_Dimm3
            size: 4GiB
            width: 64 bits



>uname -a
Linux CJ-Server 6.5.0-26-lowlatency #26.1-Ubuntu SMP PREEMPT_DYNAMIC Tue Mar 12 10:29:17 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux



>cat /proc/meminfo | grep -i memtotal
MemTotal:        7908244 kB

 

[8tg]

990FX is super picky with ram, it’s pretty common for channel B to just outright not work with some memory. It could be a whole bunch of things but there’s a ton of ancient forum posts about similar issues, and the synopsis is some stuff just not on QVL’s genuinely doesn’t function. 
Could be anything from a faulty memory controller to failing power distribution on the board to just the bios not playing nice with your memory kits.

[OC-K1NG]

Yeah, that's the direction I was thinking also.  I didn't say before but I have been a technician/engineer in the IT industry for over 20 years and have dealt with lots of similar cases, all of which got solved eventually.  But thought it was worth asking on here as thousands of minds is better than 1, plus it always seams to be a pain when its your own hardware lol.

 

Thanks for your time and help @8tg

[OC-K1NG]

Just a quick update

 

I tried everything you can imagine, from reflashing the BIOS/UEFI, rebuilding the PC, OS install to changing the hardware (where possible).

 

Nothing worked...  I was going to give up and go to bed as it was 3am... But then, at a last ditch effort, I decided to do everything all at once, rather than only changing one thing at a time so I could troubleshoot and BAM!! everything worked, full 32GB RAM detected (4x8GB).  The only thing I cant get running at full speed is the CPU which I've limited to 4.4GHz with no boost.  I know its not what it should be and yes something like the CPU or motherboard it trash, but hey, it works for now.  Thanks again.