Any chance you could take a look at the Biostar TA890GXB HD BIOS? It's an AMI BIOS and is fairly limited as to the options included. I'm using it as a low power server w/ a 45W CPU and would ideally like to undervolt the CPU. The BIOS only provides options to increase the voltage. I'd also like the option to turn on IOMMU if possible. You can download the BIOS here:
http://www.biostar.com.tw/app/en/mb/bios.php?S_ID=478

Thanks!!