[SOLVED] Available memory incorrect

[sdamaged]

Hi,

 

I have 4 x 16GB Crucial ECC RAM inside my Asrock Pro4 board, all detected fine inside the BIOS and showing inside the info section of unraid

 

However, the usable RAM seems to only be 32GB, and i can't work out why

 

I am on the latest BIOS and the RAM is supported on the board by Asrock.  No onboard video consuming RAM, its got a discrete card

 

The RAM is seated correctly (or wouldn't show in the BIOS)

 

Any ideas?

 

 

Edited March 7, 2021 by sdamaged

[sdamaged]

Hmm, ran memtest and only showing 32GB.... i need to see wtf is going on here

 

OK tried every stick of RAM one at a time, and all good and detected in memtest.  However, i can't get more than 2 sticks of RAM to show in memtest, despite all four showing in the BIOS.  Memory is set to auto speed (2666) with default settings.  Very confused 

Edited February 13, 2021 by sdamaged

[JonathanM]

Possibly a BIOS setting?

[sdamaged]

I went through the BIOS options one by one, and nothing seemed to affect it. I increased the voltage from stock and also tried dropping the memory speed.  Made no difference.  BIOS shows 64GB, but memtest and unraid both only show 32GB.  

[JonathanM]

13 minutes ago, sdamaged said:

I went through the BIOS options one by one,

Did you find anything like Above 4G Decoding, or Resizing BAR, or Resizable BAR, or Re-Size BAR Support?

Also, try toggling UEFI

[sdamaged]

There is an option for Above 4G Decoding, but that's only relevant for GPUs?

 

This is the RAM i have, its dual ranked, which should work on all four slots @ 2666 - CT16G4WFD8266

 

CPU is the 1600 AF which i believe is classed as Pinnacle Ridge

 

 

Edited February 13, 2021 by sdamaged

[sdamaged]

Could be related to the IMC on the Ryzen CPU.  Zen+ might not have the juice to run 4 RAM sticks.  Ill try a newer CPU

[sdamaged]

This is fixed.  Changed CPU to a 3900X and it sees all 64GB.  Obviously a weaker IMC on the older Ryzen chip