Intel Core i7-975 Extreme Edition/950 Performance Preview

It's almost closing time for Intel's Core 2 line of dual-core and quad-core processors. After successfully introducing their next-generation Nehalem CPU architecture at the end of last year with the Core i7 processor family for high-end desktop PCs, in a matter of months Intel will trickle that technology down to mainstream systems which are currently outfitted with Core 2 processors. While Intel hasn’t officially announced the brand name for their new mainstream processor line, we all know its codename: Lynnfield.

All indications suggest that Lynnfield is going to be a serious performer capable of outrunning not only Core 2, but even Intel’s most affordable Core i7 offering, the Core i7-920, once the fastest Lynnfield processors are available. Current rumors indicate clock speeds at launch may be as high as 2.93GHz, with less expensive Lynnfield models clocked at 2.8GHz and 2.66GHz. Pricing on these chips is rumored to be $562, $284, and $196 respectively.

With so much power on tap for the mainstream desktop PC coming shortly with Lynnfield, the performance line separating Core i7 from everything else is about the be blurred.

Intel doesn’t want this though. Intel wants Core i7 to always be the processor for enthusiasts who crave maximum performance. Therefore in order for Core i7 to remain at the top of the heap, today Intel’s introducing faster Core i7 processors starting at clock speeds of 3.06GHz.

Essentially today’s Core i7 CPU releases are intended to help distance the i7 platform from Lynnfield, paving the way for both Intel platforms to dominate the CPU landscape for the foreseeable future. Life’s about to get tougher for AMD.

The Core i7-975 Extreme Edition is Intel’s new flagship processor. Clocked at 3.33GHz with 8MB of L3 cache and 6.4 GigaTransfers/sec QPI speed, the chip is basically a more extreme version of the Core i7-965 Extreme that launched last year. The architecture is the exact same, with the chip featuring an unlocked clock multiplier allowing for maximum flexibility when OC’ing.

While it’s officially launching today, the arrival of the 975 Extreme Edition isn’t unexpected, the chip actually made a guest appearance on xtremesystems.org in February of this year. The chip in question was OC’ed to an astounding 5.25GHz with a Gigabyte GA-EX58 Extreme motherboard and 1.5V of juice. In the thread it was revealed that the Core i7-975 EE would be the first chip to launch with Intel’s then new D0 stepping, which offers improved OC’ing headroom (among other improvements) versus the original C0 stepping. (D0 has since trickled down to the Core i7-920, be on the lookout for 920 CPUs with the SLBEJ S-Step.)

The other processor Intel is launching today is the Core i7-950. The 950 is Intel’s new middle range Core i7 offering, sporting a clock speed of 3.06GHz and 4.8 GT/sec QPI speed.

Essentially the Core i7-975 Extreme replaces the Core i7-965 Extreme Edition, while the Core i7-950 replaces the i7-940 in Intel’s lineup. The Core i7-975 Extreme Edition is priced at $999, while the Core i7-950 lists for $562. Intel has no plans to drop the price on existing Core i7 processors, officially the 975 sells for the exact same price as its predecessor, while the 950 sells for the same $562 as the 940. Think of it as a free performance upgrade from Intel if you were just about to pick up a Core i7 940 or 965 EE CPU.

To evaluate the new processors, Intel sent over a shiny new Core i7-975 Extreme Edition CPU (we merely downclock it to get 950 performance numbers). Eager to see how much of an improvement the new CPU brings in terms of frequency scaling, we quickly popped the CPU into an open spot on the test bench and began OC’ing.

Overclocking

At stock voltage, our Core i7-975 Extreme sample maxed out at 3.86GHz (29x133.6) when OC’ing. Anything beyond that and stability began to become an issue.

From there we set the CPU voltage setting to “auto” in our Gigabyte motherboard’s BIOS, as it actually does a good job of determining the voltage required to meet the needs of the processor, even when OC’ed.

Slowly but surely we dabbled with multiplier and base clock settings, until we ultimately settled on a max stable speed of 4364MHz (32x136.4). At this speed we needed 1.4V of juice for the CPU.

We could actually push the processor even higher and run some benchmarks, but we couldn’t get complete stability in everything we like to run for testing. We did get some nice runs in Crysis at 4.5GHz though, and took a nice snapshot of the speed in CPU-Z:


Our testbed platform for the Core i7-975 Extreme Edition consisted of Gigabyte’s flagship X58 motherboard, the GA-EX58 Extreme, and 6GB of OCZ DDR3 Reaper HPC memory modules. Cooling duties were handled as always by an Ultra-120 eXtreme RT from LGA1366 heatsink/fan from Thermalright.