Edit - all sorted.
Have recently rebuilt the PC it for Plex, Home Assistant and a some other apps hosted on Proxmox and would like to up the RAM from 16GB.
Seems my 11Gen Aorus Pro does not like all 4 DIMM slots filled. Even with identical model numbers. Two sets of extra RAM both tested bed earlier this year so they were returned and my lastest effort on the weekend had the box shutting down after a week's use and then not booting at all with 4 DIMMs, even after Memtest passed them.
I'm in Sydney this week so thought I might try and pick something up if there's a bargain to be had.
Best I can find is $140-$150 for some Silicon Power and Kingbank.
Thanks.
2x modules for dual-channel mode will provide better memory transfer performance.
You may have some bent cpu socket pins affecting use of the additional slots.