Hey,
a few days ago I successfully flashed an ASUS M5A97 bios (version 0705 to 1605). No problems whatsoever, whereas the BIOS-builtin "AZ Flash 2" turned out to be useless: it didn't even recognize my FAT usb stick.
$ sudo /usr/local/sbin/flashrom --programmer internal -w M5A97-ASUS-1605.ROM flashrom v0.9.6.1-r1646 on Linux 3.7.5 (x86_64) flashrom is free software, get the source code at http://www.flashrom.org
Calibrating delay loop... OK. Found chipset "AMD SB7x0/SB8x0/SB9x0". Enabling flash write... OK. Found Winbond flash chip "W25Q32" (4096 kB, SPI) at physical address 0xffc00000. Reading old flash chip contents... done. Erasing and writing flash chip... Erase/write done. Verifying flash... VERIFIED.
Output from "flashrom -V --programmer=internal" attached.
W25Q32 ... chip already listed as supported AMD SB7x0/SB8x0/SB9x0 ... chipset already listed as supported -> ASUS M5A97 ... mainboard *NOT* listed yet
Thanks for flashrom! m.