For athlon 200GE it needs to have bios rev 4011.
You can get it from this page:
ASUS Prime motherboards are expertly engineered to unleash the full potential of AMD and Intel processors. Boasting a robust power design, comprehensive cooling solutions and intelligent tuning options, these ASUS motherboards provide daily users and DIY PC builders a range of performance tuning...
www.asus.com
I'm pretty sure you need a functioning board to update BIOS on Asus products...that means you have to have access to a processor that your current BIOS does support.