[flashrom] Flashing iPXE rom on motherboard NIC

Hi,

I did an attempt just to see if flashing a ROM works on my motherboard
before flashing i-PXE rom.
I try to backup with command: flashrom -p internal -V -r biosback
Then flashing the same backup: flashrom -p internal -V -w biosback
No error occurs and after a reboot the system is OK.

I am frightened to destroy entire BIOS while flashing an i-PXE rom on my
onboard NIC.
The previous mentioned backup is 1,048,576 bytes and seems realy large
and may be it contains bios data other than PXE code.
I have doubt where the program retrieve and write his data because there
is no atheros feature for it.

I want to know if there is any danger to alter the entire BIOS if I
flash an i-PXE ROM on my onboard NIC ?

Thanks