Intel Core i7: Nehalem Launched

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Intel Core i7: Core Overhaul

November 8, 2008 by Lawrence Lee with Mike Chin

The release of the Core line of desktop processors was Intel's great redemption. After struggling for some years to compete with AMD's Athlon 64 line, Intel abandoned the NetBurst architechture of their Pentium 4 and Pentium D chips in favor of Core and Core 2. The Core 2 took back the performance crown and Intel regained much of the market share it had lost, forcing AMD to drop prices in order to compete at least in the middle and low end of the processor market, at great financial cost. To this day, no AMD dual core processor can outperform the fastest of the initially released Core 2's, the 2.93Ghz Core 2 Extreme X6800, released all the way back in July of 2006, an eternity in the life cycle of processors; AMD still has a lot of catching up to do. While it has been a great run for Core 2, Intel is not resting on its laurels now. The next generation Core i7 is here, and with it, Intel is pushing to keep its lead into the future.

A Core i7 processor. Bare on the left, with heatspreader in the center, and the back side on the right. No, it's not quite square.

The Core i7 line is the first release of Intel's new Nehalem architechture. Though it is built on the same 45nm process as current Core 2 processors, Nehalem is not simply the next generation of Core — it is a drastic re-design in many respects. First and foremost, the processors feature an integrated memory controller — a move that proved very advantageous for AMD's Opteron and Athlon 64. Having a memory controller built directly on the CPU die allows CPU/memory operations to bypass routing via the northbridge chip. This increases overall memory performance and frees up bandwidth for other interfaces; multiple cores benefit greatly. The controller also supports triple channel memory, presumably a step above dual channel.

A Nehalem die.

Following in the footsteps of AMD once again, Intel has developed their own version of HyperTransport called QuickPath Interconnect. QPI allows for a 20-bit wide 25.6 GB/s link between the CPU and northbridge — doubling performance compared to the maximum 1600Mhz Front Side Bus available currently on Intel platforms. Nehalem also sees Intel's return to Hyper-Threading, a feature from the Pentium 4 era not present in the Core 2 line. There are plans for 8 core Nehalem processors capable of dealing with 16 threads simultaneously.

Power management is handled differently as well. Each Core i7 chip has a PCU (Power Control Unit) which can alter core frequencies and voltages dynamically depending on load. When the cores are idle, PCU can underclock and undervolt them to use less power or put them in a sort of standby mode where they use almost no power at all. To complement this, Turbo Boost Technology will overclock active cores while the idle ones are asleep — as many programs cannot fully take advantage of 4 cores, a boost in clock speeds of the ones they can use is useful. Turbo mode will also overclock all cores if it deems that the processor is receiving sufficient cooling.

With all these changes comes a new socket, LGA 1366. Enthusiasts often cry in outrage when a socket change occurs, usually because it's seen as unwarranted money-grab that requires not only a new CPU for an upgrade but new motherboard and heatsink as well. This time around, with all the changes to the architecture, the die size is much larger so a new socket appears to have been unavoidable. The thing does have 1366 contact points!

The Core i7 line, code-named Bloomfield, is currently comprised of three quad-core chips. They each have 256KB of L2 cache per core, 8MB of L3 cache and TDPs of 130W. The 920 runs at 2.66Ghz, the 940 at 2.93Ghz, and finally the 965 Extreme which runs at 3.2Ghz. Pricing is set to be $284, $562, and $999 USD respectively in large qualtities for Intel's biggest buyers.

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