I know some people have tried the k7s6a bios on the k7s5a board with bad results. All the pci slots go dead and the board is barely functional. I don't believe that the k7s5a can have multiplier options added with a simple bios tweak. The way the board reads the multiplier is hard wired to the socket and thats why the multiplier mod over at ocworkbench involves taking apart the socket and breaking pins to gain ability to change the multiplier. With that said there is a huge thread over there trying to figure out a backdoor method to change multiplier and I hope the pull it off.