UEFI-Only BIOS in Lenovo Xiaoxin | Generated by AI

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Question: Can’t find a UEFI/Legacy toggle in Lenovo Xiaoxin BIOS (id string LACN36WW) — where is it, or does it even exist?

Answer: I couldn’t find exact documentation for LACN36WW specifically, but based on the naming pattern (XXCN36WW), this matches recent Lenovo consumer BIOS builds (Insyde H2O firmware) used on 2022+ Xiaoxin/IdeaPad/gaming models. Important: most of these newer Xiaoxin models don’t have a Legacy/CSM toggle at all — they ship UEFI-only. So if you’re not finding it, that’s likely because it genuinely isn’t there, not because you’re looking in the wrong place.

To confirm, get into BIOS first:

  1. Power off completely.
  2. Press the Novo button (tiny pinhole button on the side, next to power port) with a paperclip, OR power on and immediately mash Fn+F2 or F2.
  3. You’ll land in Insyde H2O setup — tabs across the top: Main / Configuration / Security / Boot / Exit.
  4. Check Boot tab — look for “Boot Mode,” “UEFI/Legacy,” or “CSM Support.” If it’s just showing “Boot Mode: UEFI” with no dropdown/other option, that confirms UEFI-only firmware — nothing to change here.
  5. Check Security tab for Secure Boot — this is more likely to matter on these models. Try toggling it off if it’s on (Windows 11 installs fine either way, but sometimes a fresh GPT disk with Secure Boot enabled + missing ESP trips up).

Given this, my earlier “CSM/Legacy mismatch” theory is probably wrong for your hardware — since it’s UEFI-only anyway, the missing ESP on Disk 0 was actually caused by something else: likely you ran convert gpt on a disk that Windows Setup then still treated with an MBR-style partition creation because the partition style flag was stale from the previous clean — or Setup was in a weird state from the earlier failed attempt.

Simplest fix, skip the BIOS hunt: just redo the diskpart clean fully fresh:

diskpart
list disk
select disk 0
clean
convert gpt
exit

Then Refresh → select unallocated → Next, and check carefully this time whether EFI System Partition appears in the list after Setup auto-creates partitions (before you click Next again). If it appears, you’re fine regardless of BIOS boot mode.

References:

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