If it's a retail box, then no, afaik the CPU will be just as good as any other retail CPU bought from elsewhere.
With my 4930K from OCUK, I struggled for a long while to get 4.4GHz (even now I'm still having stability issues in certain stress tests at 1.365vcore, that I'm tempted to just pack it in, sell it and buy a new chip and hope for the best). The thing just does not like anything higher. Though, from what I'm told, I probably have one of the worst 4930K's around.
As always, it is silicon lottery.
EDIT: To add to that: I also had a 3770K from OCUK that did a wicked 4.8GHz at a nice 1.28V, all bench stable. A friend bought the same CPU at the time from OCUK and couldn't get 4.2GHz without 1.3V. Point is, it doesn't matter where you purchase, the lottery applies everywhere.