NehalemCalc warns you, if the QPI clock is too high. (picture: PCGH)
Depending on selected default clock speed (BClock) and multiplier the tool adjusts the expected frequencies. If you increase the QPI clock to more than 4,000 MHz for example, NehalemCalc warns you of possible instability.
The Core i7 OC tool also notices if the Uncore multiplier isn't at least twice as high as the memory multiplier. The Uncore clock spans the memory controller and derives from the default clock speed.
You can find the up-to-date version of NehalemCalc in the
Icrontic forum.