Hi
I use a couple of HP MicroServers for my clients:
HP MicroServer Gen 8: Intel Celeron, or Xeon Quad Core CPUs, max RAM 16 GB.
CPU is not Hyperthreaded, shows up in Proxmox as 4 CPUs. 2 NICs.
HP MicroServer Gen 10: AMD Quad Core CPUs, max RAM 32 GB. No ILO / IPMI. CPU is a little underpowered. CPU is not Hyperthreaded, shows up in Proxmox as 4 CPUs. 2 NICs.
HP MicroServer Gen 10 Plus: Intel Quad Core CPU, max RAM 32 GB Official supplied, or 64 GB if you get your own. Optional ILO / IPMI. CPU is not Hyperthreaded, shows up in Proxmox as 4 CPUs. CPU can be replaced with a Intel 6 core with Hyperthreading, shows up in Proxmox as 12 Cores. This box is only half the size of the above two, but has the most options. 4 NICs.
I have a Gen8 at home, also running TrueNAS with a System-SSD and 2*4 TB WD Red Disks.
This has 16 GB RAM.
I also have a HP Microserver Gen 10 Plus, this is running as Proxmox.