@yann Good catch. I tend to use net install when available, as it is faster than emulated iso on supermicro motherboards. When trying beta 2 install, I did use the network source by using xcp-ng-8.3.0-beta2-netinstall.iso.
To test things further, I used my backup server (Supermicro X10DRT-H, with E5-2630 V3) and disabled execute disable bit. Verified that 8.3 RC1 install gives the same error "Xen requires NX support" and ran beta 2 install from local media. This time 8.3 beta 2 was installed without issues and after a reboot I verified that execute was still disabled in the bios.
When using RC1 installer:
Beta 2 installer with local media this time: