You have to ask yourself, "why would Intel want to screw its high-volume OEM purchasers by selling them substandard parts"?
I can't think of any particular reason why Intel would want to sell higher-quality parts in retail boxes to people who are frequently going to overclock and otherwise abuse the CPU...that user will buy a CPU every couple of years, while the high-end OEMs will buy CPUs by the pallet-load.
