Asrock X99 Extreme11 reports only 48GB

lmax25 wrote: Hello !   My new Asrock X99 Extreme11 MB reports only 48GB of RAM instead of 64GB of RAM. I have Bios version 3.20. I installed HyperX Savage Black 64GB DDR4 2400MHz CL14 Quad Channel Kit manufacturer code : HX424C14SBK4/64 and CPU Intel® Core??i7-6850K, 3.60GHz , Broadwell, 15MB, Socket 2011-V3   Please tell me how to configure the RAM from BIOS to use all 64 GB of RAM installed.   Thank You !

"Missing memory" is not uncommon when larger capacities are used on X99 systems. If only it was just some option settings that would easily fix the issue, but that is not a given.

Apparently one DIMM is not being recognized, have you identified the memory slot in which it is mounted?

What is telling you that only 48GB is being recognized? Windows? The UEFI/BIOS? Both?

If you open Resource Monitor in Windows, Memory tab, what is shown?

Not much information given in your post, so mostly questions at this point.

Which DIMM slots are you using, the A1, B1, etc, or A2, B2, etc?

All default or Auto basic memory option settings in the UEFI/BIOS?

What speed is the memory operating at currently? Did you enable the XMP profile?

Is 48GB only recognized at both 2133 and 2400 memory speeds?

Have you done any testing to verify that all four of the DIMMs in the memory kit are working?

Initial UEFI/BIOS option settings to set and try are:

OC Tweaker, Voltage Configuration screen:

Set DRAM Voltage to 1.25V - 1.3V - 1.35V, in steps and check if the memory is recognized. Start with 1.3V and if that works you can try to reduce it to 1.25V.

OC Tweaker, DRAM Configuration screen:

At the very bottom of this screen, find MRC Fast Boot, and set it to Disabled.

Next, find Memory Test, and set it to Enabled.

You do not need to leave these option set this way permanently, but at least for several restarts/boots of the PC to allow memory training and testing to occur.