ASUS Z10PE xeon turbo hacking / .cap .rom bios flashing

What is .cap?

  • Since some update, all ASUS BIOS files must be in .cap format instead of .rom format
  • .cap format is raw .rom format with 2048 bytes header prepended
  • The header is likely to be some sort of cryptographic signature and/or checksum
  • EZ flash check this header, while BIOS flashback does not

My case

  • Z10PE-D8 WS BIOS, 3407
  • Haswell microcode removed
  • me_cleaner with -S option applied
  • Original 3407 .cap header is prepended into the modded .rom, it became the file below
  • Rename the file downloaded to Z10PEWS.CAP and put it into root of FAT32 USB drive, start BIOS flashback, success for me.

.cap to .rom?

$ dd if=Z10PE-D8-WS-ASUS-3304.CAP of=Z10PE-D8-WS-ASUS-3304.rom bs=1024 skip=2 as mentioned in Just remove the first 2048 bytes.

.rom to .cap?

Since .cap is signed and EZ flash checks it, it is NOT possible to flash a modded .cap unless you know how is it signed.

But, if your motherboard supports BIOS flashback

  1. $ head -c 2048 Z10PE-D8-WS-ASUS-3407.CAP > modded.cap
  2. $ echo your-modded.rom >> modded.cap
  3. $ mv modded.cap MB_CAPNAME.CAP
  4. You can now flash the .cap you made. For names and method please refer to


Last modified: 2018-06-20 16:47:43
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