May I know if going to install 64GB RAM on QNAP TS-h973AX will it able to see 64GB RAM installed? as I watched your video (64GB, 32GB and ECC memory in the QNAP TS-873A NAS – Memory Upgrade Test) TS873A and TS-h973AX are using same CPU.
Yes, the limit is always based on a CPU, not the NAS model.
So in this video, we tested Kingston 32GB memory which worked and also could be used in virtual machines.
Yes, you can upgrade this NAS with ECC memory. This will require removing the existing non-ECC module. But this is the right thing to do if you want a more reliable system. Not only ZFS files system can benefit from this, but any other file system too. Very useful for things like VMs, web servers etc.
Here is a list of Qnap ECC RAM:
not tested on our side
Kingston Server Premier KSM26SED8/16HD Memory 16GB 2666MHz DDR4 ECC CL19 SODIMM 2Rx8 Hynix D