I wonder what the rationale for 18 cores was, since it's a rather unusual number of cores and not a round number - 16 would be the usual choice. Was it just "we can put two more on the die, so let's do that"?
Well, the biggest Ivy Bridge EX has 15 cores! There's speculation that the 18 core Haswell-EPs are actually Haswell-EX dies that Intel wants to get rid as fast as possible because these chips have buggy TSX (transactional memory).
