I have the Z97 Extreme6 Socket 1150 motherboard and have been using 2 x 4GB G.skill Ares RAM DIMMs without issue.

However, I have added another 2 x 4GB of the same DIMMs and the extra 8 GB is showing up in the Memory tab of the Resource Monitor as "Hardware Reserved".  In the Performance tab of the Task Manager it says the total physical memory is 8192 MB.

The model no. of the DIMMs is GS-F3-1600C9D-8GAO.  On the G.skill website https://www.gskill.com/en/product/f3-1600c9d-8gao" rel="nofollow - here it says that the RAM has been tested on my motherboard.

However on the ASrock Support site https://www.asrock.com/MB/Intel/Z97%20Extreme6/index.us.asp#Memory" rel="nofollow - here it does not list these DIMMs as tested working.

Prior to installing these extra G.skill DIMMs I tried a 1 x 8GB DIMM (standard G.skill model F3-1600C11S-8GNT) and I had the same issue.  I had the original 2 x 4GB DIMM's installed in slots A1 and B1 as is suggested for matched pairs.  I tried swapping these around with the single 8GB DIMM every way and I would always see the additional 8 GB as Hardware Reserved.

I have installed the newest 2 x 4 GB DIMMs into slots A2 and B2 as would expected with a second  matched pair.

Is there anything I can do to get the additional 8 GB to be usable?

Thanks in advance for the help!

I forgot to mention that I'm using WHS 2011 - which has an 8 GB RAM limit!!

So unless anyone knows a way to get around this limit... I think I'm stuffed!

It's basically a media server with a tonne of storage running Plex, Sonarr, Radarr, Headphones, etc.  The storage effectively uses software JBOD (StableBit DrivePool).

I want to run a macOS VM so that I can install an iMessage server (long story!).  I have this running through VMware Workstation Player and it's suggested that a minimum of 4GB RAM is assigned to this.

I've got it running well with 3.5 GB and WHS 2011 still runs reasonably well but it's always sitting at 7GB+ RAM consumed.  I'd like to have a bit more headroom.

I would consider virtualising my copy of WHS 2011 and running it as a VM inside my new Linux installation.  Obviously alongside this I could run macOS.  It looks like I'd have to upgrade to Workstation Pro in order to be able to run more than 1 VM simultaneously.

Also note that I originally used VirtualBox for the macOS VM and it kept locking up.  I haven't had any issues with Player so far.

It would probably be ideal if I were to ditch WHS 2011 and install a new host OS however I've spent a lot of time and effort in getting the software on it running properly so would prefer to keep this running for as long as possible.

Which would be the best Linux distro to go with for a host OS?  I would be looking for stability and minimal system resources over looks and features, as it will need to run 24/7 and I will likely not install much on it other than the hypervisor software.

Thanks!