RAM not loading

[JackH124]

My system has 4 8GB DDR4 ECC 2400HMz Micron memory but on the BIOS, and in Windows it says that there is only 16GB installed. However, when I used CPU-Z all 32GB is showing up.

I; 've tested every stick individually in every DIMM slot and it worked fine. I've tested every stick in DIMM1/3 and DIMM2/4 and it works correctly.

The problem only arises when all 4 DIMMs have RAM inserted it says that DIMM1 and 3 have no RAM.

[BeemerBiker]

Make sure your maximum memory is unchecked

The service manual for z240 is here

http://www1.hp.com/ctg/Manual/c04897695

I assume you have a GPU and it has its own memory.  If not you might check the bios for how much memory to allocate

Video Memory Size
Use this option to manage graphics memory allocation. The value you choose is allocated permanently to
graphics and is unavailable to the operating system.

There should be a memory test built into the BIOS.  There is also one in windows.  Please run both tests.  If  no bios memory test or if it cannot do ECC then get memtest or the latest version of memtest.  Create a boot USB to run it.

There is a discussion on page 17 about non uniform memory and how to configure interleave that could be tried.

There is probably a memory incompatibility.  Try using 3 sticks fill in the 1,2,3 slots as shown in picture page 55 and see if 24gb works.

Good Luck!