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When I make bootable USBs and plug them in to my main computer, There are (almost) always two UEFI partitions, like here: x399 Taichi BIOS ^^Note that in this picture "USB: Samsung flash drive 1100" is a different USB stick also plugged in. The same thing has happened many times without it. It doesn't seem to matter, selecting either boots equally well into uefi mode (as verified by ls /sys/firmware/efi/efivars).

However, plugging this same USB into my laptop only shows 1 UEFI partition: Dell BIOS

Since in all cases I had zero filled the SSD key and then made a USB from a prepared ISO (Both Arch and Ubuntu Server ISOs), I wouldn't expect there to be more than one UEFI partition, anything remaining from previous use should be wiped out. This happens with multiple drives of different makes (mostly Samsung and SanDisk Cruzer Glide).

I'm guessing that the extra UEFI is just some minor motherboard bug, but I'm still curious about what the exact cause might be.

The motherboard in question is an ASR x399 Taichi.

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If your computer has ghost entries in the boot menu, you may get rid of them using the efibootmgr utility, whose purpose is to manipulate the EFI Boot Manager.

To list boot entries:

sudo efibootmgr

Note the number next to "USB: Samsung flash drive 1100. Partition 2", which will have the format of "BootXXXX".

To delete the entry "XXXX" do:

sudo efibootmgr -b XXXX -B
  • Holy crap, there were like 10 boot section on that drive! How can that be after zero-filling? – Stonecraft Jun 15 at 17:15
  • One other question: Is there some way to do with without booting from the volume I wish to clean? It would be nice to be able to just plug in a usb stick, issue a command, and know that it is well and truly clean. – Stonecraft Jun 16 at 6:10
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    I don't know of such a method. – harrymc Jun 16 at 6:12

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