Disclosure: I am contributing on behalf of ICT Sai Gon, a Vietnamese computer retailer. This is an AI-assisted documentation summary, not a report of hardware I have tested.
For a mini-PC PVE host, there are two separate checks before purchasing more RAM.
1. Confirm the physical upgrade path
Use the exact system or motherboard model to check its memory specification: soldered versus replaceable memory, module form factor, DDR generation, supported capacity per socket, total capacity and BIOS requirements. A small case does not by itself prove that the machine uses SO-DIMMs. Matching capacity alone is insufficient.
Kingston's glossary explains the distinction between SO-DIMMs, registered DIMMs and unbuffered modules:
https://www.kingston.com/en/memory/kingston-glossary
For Vietnamese readers, our illustrated DIMM/SO-DIMM reference includes a model-checking checklist and links to the underlying manufacturer documents:
https://ictsaigon.com.vn/dimm-va-so-dimm
2. Budget host and guest memory separately
Passing the hardware check does not mean all installed RAM should be assigned to VMs. Leave capacity for the PVE host, virtualization overhead and other host services; account for ZFS separately if it is used.
In PVE, setting a VM's minimum memory equal to its maximum gives a fixed allocation. Setting a lower minimum enables dynamic allocation through the guest's balloon driver. Ballooning does not increase the machine's physical RAM, and its behavior depends on guest support. The manual specifically cautions about ballooning on critical Windows systems.
Planning example only: on a hypothetical 32 GiB host, three fixed 4 GiB VMs allocate 12 GiB. The remaining nominal 20 GiB is not automatically available for another VM: host services and other overhead still have to fit. This is arithmetic, not a workload benchmark or sizing guarantee.
Official PVE memory-allocation documentation:
https://pve.proxmox.com/pve-docs/chapter-qm.html#qm_memory
For a mini-PC PVE host, there are two separate checks before purchasing more RAM.
1. Confirm the physical upgrade path
Use the exact system or motherboard model to check its memory specification: soldered versus replaceable memory, module form factor, DDR generation, supported capacity per socket, total capacity and BIOS requirements. A small case does not by itself prove that the machine uses SO-DIMMs. Matching capacity alone is insufficient.
Kingston's glossary explains the distinction between SO-DIMMs, registered DIMMs and unbuffered modules:
https://www.kingston.com/en/memory/kingston-glossary
For Vietnamese readers, our illustrated DIMM/SO-DIMM reference includes a model-checking checklist and links to the underlying manufacturer documents:
https://ictsaigon.com.vn/dimm-va-so-dimm
2. Budget host and guest memory separately
Passing the hardware check does not mean all installed RAM should be assigned to VMs. Leave capacity for the PVE host, virtualization overhead and other host services; account for ZFS separately if it is used.
In PVE, setting a VM's minimum memory equal to its maximum gives a fixed allocation. Setting a lower minimum enables dynamic allocation through the guest's balloon driver. Ballooning does not increase the machine's physical RAM, and its behavior depends on guest support. The manual specifically cautions about ballooning on critical Windows systems.
Planning example only: on a hypothetical 32 GiB host, three fixed 4 GiB VMs allocate 12 GiB. The remaining nominal 20 GiB is not automatically available for another VM: host services and other overhead still have to fit. This is arithmetic, not a workload benchmark or sizing guarantee.
Official PVE memory-allocation documentation:
https://pve.proxmox.com/pve-docs/chapter-qm.html#qm_memory