> As far as I know, all x86 hardware should support MBR You are mixing up MBR (which is a disk partition schema) with the BIOS (old, pre UEFI) and CSM (litera

> As far as I know, all x86 hardware should support MBR You are mixing up MBR (which is a disk partition schema) with the BIOS (old, pre UEFI) and CSM (literally UEFI Compatibility Support Module) boot processes. Everything post 2012[0] is UEFI, most of time with CSM support but there are some machines without CSM at all. You are really booting in UEFI and then it loads a CSM which proceeds with "legacy" boot mode. T420 uses QM67 which is a second generation after Ibex Peak which was the first one to implement UEFI on Intel platform. ie: https://pcsupport.lenovo.com/us/en/products/laptops-and-netbooks/thinkpad-t-series-laptops/thinkpad-t420/downloads/ds018785 https://pcsupport.lenovo.com/us/en/products/laptops-and-netb... [0] Basically post Nehalem