The computer comes with Windows 11 Pro preinstalled - not to the normal Out Of Box level but boots directly to the desktop. Out of curiosity, I installed windows 11 from scratch - or tried to do so. Windows refuses to install as the CPU is not supported and the board/bios does not support Trusted Platform Management (TPM); so, to reinstall windows 11 a modified version of the installation is required. This is not difficult to do but is also not valid per Microsoft.Just be aware of what you are buying!As I never intended to leave Windows 11 on this machine it is a non issue for me.Windows 10 22H2 Enterprise installed without issue.