Since UEFI is preferable, I’m wondering why I don’t read much about MBR vs GPT partitioning of Unraid’s USB flash drive. I understand to enable UEFI you have to have the folder called “EFI” instead of “EFI-“

But is that really it? Everywhere else generally emphasizes having GPT partitioning for UEFI.

I can’t seem to figure out the interaction between this, and the ‘Launch CSM’ and ‘OS Type’ (“windows UEFI” or “other os”) settings in my bios (an ASUS H110i, with i5-6400), which affect legacy support / UEFI / secure boot in different ways. My understanding is that I want UEFI, but no secure boot. I also have read about possible issues with the Intel iGPU not functioning under some of these settings, and indeed I will get a blank screen if I disable CSM.

Create your bootable media | Unraid Docs

Unraid OS is installed on a USB flash drive, which acts as the boot device for your server. You can create this bootable media using our recommended Automated install method with our USB Flash Creator

I believe its more to do with the usb and its GUID ... unraid unique GUID is required for licensing... this is alos usb size specfic...

Short answer: for Unraid’s flash, GPT vs MBR basically doesn’t matter for UEFI boot. What matters is a FAT32 volume with the standard UEFI fallback path present. Unraid ships Syslinux’s UEFI loader under /EFI on the flash; if that directory is named EFI (not EFI-), your board will UEFI-boot it. That’s why you mostly see “rename EFI- → EFI” and not “convert to GPT.”

Boot & startup failures | Unraid Docs

When your Unraid server fails to start correctly, it can be challenging to identify the cause without a clear understanding of the boot process. Following this guide lets you quickly diagnose and reso

Why that works

• UEFI is defined to look for a default loader on removable media at \EFI\BOOT\BOOTX64.EFI (the “fallback path”), and it can do that regardless of whether the stick is MBR or GPT. Many firmwares will happily UEFI-boot a removable FAT32 device that’s MBR-partitioned.

• Unraid’s flash creator simply uses one FAT32 partition (traditionally MBR + “active” flag for legacy-compatibility). The “active” flag is ignored by UEFI; the presence of the EFI folder is what flips UEFI on.

Secure Boot is mainly the problem Winndwos BS on a key and text chip for licensing... Its not secure and gets int eh way of recvrey...

• Unraid still doesn’t support Secure Boot. Leave Secure Boot disabled. (Enabling it with “Windows UEFI” keys will block the Syslinux loader. sometimes...)

• https://uefi.org/specs/UEFI/2.10/03_Boot_Manager.htm

ASUS H110-series BIOS knobs (what to set)

• OS Type: set Other OS (this disables Microsoft Secure Boot enforcement).

• CSM: If your display initializes fine, you can set Launch CSM = Disabled for “pure UEFI.” If you get a black screen, keep Launch CSM = Enabled but set:

  • Boot Device Control = UEFI and Legacy OPROM, and

  • Boot from Storage Devices = UEFI driver first
    This lets the firmware use a legacy video Option ROM for display while still booting Unraid in UEFI mode.

• Boot order: pick the entry that starts with UEFI: for your flash drive. (Unraid UEFI boot only needs the EFI folder present; no extra “make bootable” step.)

About the Intel iGPU “blank screen when CSM is off”

• That’s a firmware/GOP quirk: with CSM off, your board must initialize the iGPU via a UEFI GOP driver; if it doesn’t, you see no pre-OS video. Workarounds that usually fix it: update to the latest BIOS, set Primary Display = CPU Graphics, optionally enable iGPU Multi-Monitor, and try HDMI instead of DP during POST. If it still blanks, just leave CSM enabled with “UEFI driver first” as above; Unraid will still boot in UEFI.

Practical checklist for your stick (ASUS H110i + i5-6400):

1. Use the Unraid USB Creator (or your existing stick). Ensure it’s FAT32 and the top-level folder is EFI (not EFI-).

2. In BIOS: Other OS, Secure Boot = Disabled, and either CSM = Disabled or CSM Enabled + Storage “UEFI driver first.” Then boot the UEFI: entry for the flash.