Efficiency Explored: Core i7-980X Versus Core i7-975

Six Cores And 32nm Versus Four Cores And 45nm

Although we know AMD has its own plans to launch a six-core Phenom II X6, Intel gets the jump by demonstrating its own hexa-core model ahead of AMD's plans. The Core i7-980X, formerly referred to as Gulftown, will soon be available for LGA 1366 systems, and it promises new levels of performance in threaded apps able to take advantage of its increased parallelism and on-die shared L3 cache.

Thanks to the new six-core part being based on a 32nm lithography process, it reaches the same 3.33 GHz clock speed as the quad-core Core i7-975 Extreme Edition at the same 130W power envelope. Does this guarantee more performance per watt? It's hard to say without a more in-depth benchmark analysis. After all, the 1.17 billion transistor chip even fits onto a smaller die than its predecessor.

We were a bit skeptical, as Intel's first-place position seems to be resulting in specs better suited to its bottom line than platform performance. There's the lack of PCI Express 2.0 signaling in its platform controller hubs, despite advertising the links as PCIe 2.0-class. There's the fact that Clarkdale CPUs can't have their 16 lanes of PCIe 2.0 split into x8 links in H55/H57, while they can in P55. And then there's the power-saving Core i5-750S processor. Though it does indeed save power, it also gives up performance (at a higher price point, no less), which means that it actually sacrifices performance per watt. Thus, we’ll be paying particularly close attention to how Gulftown behaves with regard to efficiency.

Reviving The LGA 1366 Interface

Finally, there is a clearer reason to buy Intel’s X58 Express enthusiast platform. It has a palpable upgrade path that wasn't particularly clear when it launched back in 2008! X58's dual x16 PCI Express 2.0 capabilities are only important for graphics enthusiasts, but it's clear that Intel doesn’t plan to introduce six-core CPUs for its mainstream LGA 1156 interface any time soon. The Core i7-980X gives the LGA 1366 platform fresh legs within a more attractive price band than the one we saw more than a year ago. Back then, $350 motherboards were reasonable. Now, X58 can be had on a $150 board. You could consider purchasing an affordable Core i7 quad-core CPU today and upgrade to six-core in a year or so.

With only minor exceptions, most motherboard makers aren’t revising their existing LGA 1366 products. But as a general rule, you can look for an updated BIOS version with Gulftown support, flash it, and install the new $1,000 six-core monster.

Performance vs. Efficiency

Chris Angelini already reported on performance and overclocking results. Gulftown shows significant performance advantages on thread-optimized software, and the new Core i7-980X seems to run fine at up to 4.13 GHz nominal speed. Check out our Gulftown review for details. Now, let's get to analyzing power efficiency.