Exactly. I was just about to say that the amateurs have managed to get nearly 4ghz on a 920 with reasonable cooling. So why would anyone pay extra, and so much flipping extra, for such a miniscule clock increase?
They really, really, need to start having their high-end processors at the absolute limit. If it was 4ghz @ £1k then more people will buy that one for the out-of-the-box ease, than if it's barely faster than the processor that's £600 or so cheaper.