Quick post here, as there is a quick solution for most people having the error “ROM file is not an EFI BIOS”. I recently had this with my Asus motherboard. Even though I had double checked that I had downloaded the correct BIOS update from their support website, I received this error when I tried from my USB as well as my hard drive.

Here’s what I found out about the issue. The device being read from to get the ROM file must be formatted as FAT32, not NTFS. While you can navigate file and see the file within the EFI BIOS, the underlying EZ-Flash program is separate and only reads FAT32 (and possible FAT).

So format your USB stick as FAT32, drop the file on, and try that.

Good Luck!


  • Hi Mike

    That’s because what the updater really does, is booting it´s own little micro OS and it does not support MS proprietary formats like NTFS. If the files in total are under 2Gb you can also use FAT.

  • That’s what I gathered, however you’d expect some kind of logic in there to tell you why it wouldn’t work rather than leaving you drawing a blank!

  • Perfect! congrats! Thanks!

  • Cheers !!

  • if you still get the error make sure you name the files with no – or any other symbol, keep it short to the version number and it should work then.

  • That worked for me.
    I really am greatful

  • Thanks, Mike, that did the trick!

  • I am still having the same issue even though I formatted the USB to FAT32 and remain my file to 3103.CAP. I’m sure its the right update, since i first doubled checked with the program “CPU-Z” to insure I have the right make and model motherboard (maximus Vii hero) and I downloaded the zip file: MAXIMUS-VII-HERO-ASUS-3103.ZIP.

    Steps I took are:
    check with CPU-Z
    download the listed file
    unzip that file into a *.cap
    rename the file 3103.cap
    format USB to FAT32
    cut & paste the 3103.cap file into USB
    retart PC
    Open tool, pick EZ flash
    find the file click it and BOOM “ERROR”….

  • Turns out with my ASUS EZ Flash 2 Utility v02.01; I was suppose to format the USB at NTFS and NOT FAT32…..
    only two difference from the previous listed steps i took was

    format USB NTFS
    rename my file: “myupdate.cap”

    every other step i did exactly the same and now my bios is sucessfully updated.

  • I’ve formatted my USB drive FAT, FAT32 and NTFS. I’ve tried renaming the file to the version number, or just myupdate. nothing works. i still get this same error.

    EZ Flash v2.01

  • I had trouble with the EZ Flash not reading my update file. I called ASUS support and they had me make sure the Zip drive was formated FAT32. I did this and the update file went right in. So you need to be sure the Zip Drive is Formated FAT32,

  • thank you, appreciated!

  • thank you!

  • Tanks Works very well