I wouldn't recommend using the software programs because if your OC messes up it won't necessarily be the easiest to fix all the time(if it starts up w/ the computer it can crash before you can change the setting) and resetting the CMOS doesn't help like it would for a bios overclock.
Software overclocks tend to be very generous with voltages while being modest for the clocks they actually reap from that for the sake of playing it safe with stability because the software can't easily change the settings dynamically as necessary by testing for a lot of different flaws in the OC like we can.
SB chips are easily to OC(too easy IMO) so all you should really have to do is up the multiplier and the voltage a little bit as needed. Probably a little bit more to it than that but definitely nowhere near as much as other platforms.
Underclocking would be similar but in the opposite direction.
Something else you should note is that a lower voltage doesn't always give you better temps, sometimes, it can actually RAISE the temperature.
I have my CPU OCd to 4.2ghz right now with 1.225v and it is a much bigger die but my temperatures are right around where yours are load(It's been at 68c on prime95 for the past day though). Even on stock cooling you should be getting better temps then that for where your CPU is downclocked too.
Edited by Ryleh - 3/3/12 at 9:38am