The Intel Core i7 3930K is the cheaper alternative to the top-end Sandy Bridge E processor. But then many second hand cars are cheaper than the top-end Sandy Bridge E processor.
At nearly £500 it's still an expensive CPU, but currently it's the only LGA 2011 processor worth a look.
The Intel Core i7 3960X, that top-end Sandy Bridge E, is a positively preposterous processor. For in excess of £800, you get a chip that's not substantially quicker than Intel's own Core i7 980X of two years ago.
Not at stock clocks, at least. Admittedly, the Core i7 3960X does overclock very nicely indeed and in doing so opens up a gap from ye olde 980X.
But we've reviewed the 3960X elsewhere and deemed it disappointing, moderately sinister (it's prima facie evidence of Intel carpet bagging in response to AMD's failure to bring out a really quick chip) and largely irrelevant to human existence.
This then is the Intel Core i7 3930K and it's not the same chip. Not precisely, anyway.