No offense! I cannot find any reference to a dual CPU motherboard Dell has released for the XPS 730X, is the reference to dual CPU or dual GPU, it has 2 graphics cards but Dell does not even show a dual CPU motherboard for that system.http://www.dell.com/us/en/bpi/desktops/desktop-xps-730x/pd.aspx?refid=desktop-xps-730x&s=bpi
With the CPU being an unlocked multiplier CPU all you have to do to overclock it, is raise the multiplier one step increase at a time until it refuses to boot with stock voltage.
Then you raise the stock voltage a step at the time until the increased multiplier boots, then benchmark and stress test continuing to increase the voltage a step at the time until you get the higher multiplier stable.
Write down and record your progress as you go, when you get that multiplier stable you can increase the multiplier again and continue the process of raising the voltage one step at a time until you get the next multiplier level increase stable.
Recording your results as you go you can continue with the process above increasing the multiplier, then the CPU voltage, to stabilize until it just won't boot anymore, then go back to your last stable multiplier level and that's your overclock.