Use a program like CPU-Z
' ">http://www.cpuid.com/cpuz.php and check at what Frecuency, FSB and Multiplier your Processor is running at. If it is running at 166 MHz FSB with a 10x Multiplier (1666 MHz), then you won't really need a BIOS upgrade. The only that a BIOS upgrade will do if your Processor is running at the properly settings, is that it is recognized by the BIOS as a Sempron, but that doesn't affect neither the stability or performance of the system. If not, I cannot help you upgrading your BIOS because I know nothing about neither two Motherboards, but if it let you raise the FSB to 166 MHz manually while keeping the PCI Bus at 333 MHz and work properly after that, then you still not needing it.