It's pretty simple really- go into the BIOS, set the multiplier to the desired frequency (make sure BCLK is 100 MHz) so set a 45 multi for 4.5 GHz etc. Then leave voltage on auto with automatic offset (just to see what it uses automatically). Turn LLC up to 75 or 100% (the sabertooth is a good mobo, so shouldn't have problems of voltage spikes when using extreme LLC like cheap ones do). This helps to minimise Vdroop. Then boot into windows and see what Vcore it uses under load (use a stress tester like IBT or Prime95).
If it is unstable after a few runs of IBT (I use Intel Burn Test just to quickly check initial stability before doing 8 hour runs of Prime95 when settling on my final 24/7 overclock), then set a positive offset (this will increase the idle and load voltages that the motherboard would have automatically used at that frequency). Bump it up in small increments until you reach stability. If it is stable automatically, try a negative offset (does the opposite effectively) until it is unstable. When it is unstable, back off the negative offset until you reach stability again.
Once you have found the lowest voltage to maintain stability at your desired overclock, then do around 8 hours of Prime95 small FFTs. If it is stable, then great! If it is unstable, then increase the voltage (by reducing/increasing the negative/positive offset respectively). Some people just use a fixed voltage (which is easier as it makes setting the voltage level easier) but idle temps and power consumption are better if you use offset voltage (which allows the Vcore to drop when frequency and load drop).
I'd recommend using IBT and Prime95 for stress testing, Coretemp for CPU temps and CPU-Z for Vcore.