CPU configuration for Windows Server VMs

[ProTofik]

Google gives me conflicting results so I thought I would ask here.

When running Windows Server 2022 or 2025 inside a pc-q35 10.1 VM on Proxmox 9, should I set the CPU type to x86-64 v3, or to host with nested-virt disabled?

In my case I'm on Core i5-8500.

 

[bitranox]

see this

 

[Johannes S]

When running Windows Server 2022 or 2025 inside a pc-q35 10.1 VM on Proxmox 9, should I set the CPU type to x86-64 v3, or to host with nested-virt disabled?

Both should work. In theory host should performan with disabled nested-virt should perform better since it allows to use cpu-specific instructions for stuff like compression or encryption.

You can also use a cpu type better fitted for your cpu. You following tool to determine this CPU type:
https://github.com/credativ/ProxCLMC

 

[SteveITS]

should I set the CPU type to x86-64 v3, or to host with nested-virt disabled

There are a few threads about this. The advice has changed over time because newer versions of Windows do things differently.

for instance
https://forum.proxmox.com/threads/h...sage-on-idle-with-windows-server-2025.163564/
https://forum.proxmox.com/threads/t...-of-windows-when-the-cpu-type-is-host.163114/
https://forum.proxmox.com/threads/r...-to-device-system-unresponsive.139160/page-14