Part of the reasoning behind the higher cost of Intel’s Extreme Edition processors, like the Core i7-965 Extreme Edition, is that only these processors are “unlocked”.  Only unlocked CPUs allow you to adjust clock multipliers up rather than down from the CPU default and only unlocked CPUs allow you to adjust the memory frequency on the new integrated memory controllers on the Nehalem architecture.

Are all Core i7 CPUs shipping unlocked? - Processors 2 

According to MaximumPC, ALL retail Core i7 processors, including the Core i7-940 and i7-920, are shipping as unlocked. 

Huh? To make matters worse, while mucking with our retail Core i7-920, we discovered that our QPI speeds were also unlocked. We could set it to 6.4GT/s all day. Our back channel contact tells us that after some digging, it was discovered that yes, that’s the way it’s supposed to be. QPI is supposed to be 4.8GT/s but you can run at it 6.4GT if you want. Wha, what? But two months ago, Intel insisted that QPI was locked. Now we’re told that QPI is unlocked. Confused? We are.

If this turns out to be true, then those $299 Core i7-920 processors just got a LOT more interesting…

But why lock them, and only on engineering sample parts? Traditionally, Intel’s engineering parts are unlocked so vendors can perform various tests. This is why engineering sample parts sometimes have higher values: they often have no artificial limiters on them.

Intel’s official reason for the change of heart is: “We made a marketing decision to unlock them for the launched product due to requests from some of our customers.”

Who are the customers? Intel didn’t name names but our first guess was memory makers. If memory support for DDR3/1600 was only limited to $1,000 CPUs, they wouldn’t sell a lot of high-end memory. Perhaps some OEMs even balked as well at the thought of selling machines with RAM limited to DDR3/1066.