Nehalem: The Unwritten Chapters

@ 2008/11/07
This one is a complete non-issue, but it's worth explaining. Intel's Turbo mode allows the Core i7 to ratchet up its clock speed by 133MHz or 266MHz depending on how many cores are active and if the CPU is cool enough. Every Core i7 is guaranteed to be able to work at up to 133MHz faster than its native clock speed if more than one core is active and the chip is cool enough, and 266MHz if only a single core is active and once again, the chip is cool enough.

It turns out that Turbo mode is governed by more than just temperature however, both current draw and TDP are monitored to make sure that the CPU isn't exceeding its designed specifications when running in Turbo mode. If either value is exceeded then the chip will automatically reduce its clock multiplier back to its stock setting to avoid damaging the CPU. It's sort of like the overheating protection that Intel has had on its CPUs since the Pentium 4 days; if the chip gets too hot, it underclocks itself until it's cool again.

The concern was that because of these TDP and current draw limitations, you would not be able to take lower end Core i7 processors and overclock them. The $999 Core i7-965 Extreme Edition doesn't have this problem as you can manually configure both the max TDP and current draw values, just like you can adjust its clock multiplier.

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