Well, before you give up all hope on your mobo and BIOS, you should try a couple of things. First I'd recommend that you look around in your BIOS a bit more, often you might not be able to set the CPU voltage higher ( not under that name) but you can "over volt" the CPU... and it will give you options like " +.0125v, .025v, ect". Other times those things are in your BIOS, but they're just hidden. So I'd try looking up a bit more info on your specific board. (if you havn't done that already)
Upping the chipset voltage can often bring some stability to the system, but usually that helps more when the FSB speeds are really being pushed (just like a cpu... if its running at 300, and was at 200 stock, it could use more power). You could try it, just do it one step at time and see if it helps. If it dosen't, then go back to stock.
Also, You might try flashing your bios to the latest version. Its pretty easy to do, and that can give you more options in your BIOS.
Oh and as for the CPU multi being locked... thats perfectly normal. All AMD cpu's are locked (upwards they are locked, but they can all be moved down) with the exception of the Black Edition processors. Thats what makes them such good overclockers, lots of flexibility.
Personally I use the hardware monitor that came with my mobo, and speedfan for temps... theres a link for where you can get it, and other awesome programs right HERE