Lab Tested: Intel Core i7-3960X Extreme Edition


Intel's Sandy Bridge architecture stole the limelight this year, summarily trouncing its predecessors--and the best that AMD had to offer--with considerable performance boosts and power savings. Today Intel is announcing the Sandy Bridge Extreme Edition: a $990 CPU that distills the lessons the company has learned over the past year into a single piece of premium silicon.

It's a time-honored tradition: Take all the improvements from the most recent architecture shift, and drop them into an unlocked processor aimed at overclockers and workstations with considerable computational workloads.

Sitting at the top of the Sandy Bridge Extreme Edition lineup is the 3.3GHz Core i7-3960X. Here are the specs for it and the other two newcomers (the Core i7-3930K and the Core i7-3820), in handy chart form.

Core i7-3960X up close.
The new processors are built on the Sandy Bridge architecture, and the fundamentals haven't changed. Sandy Bridge Extreme Edition offers two CPUs with six cores, and one CPU with four cores. The Core i7-3960X I examined offers 15MB of L3 cache shared between the cores--up from 12MB in last year's variant, or from 8MB in the Core i7-2600K. That larger L3 cache permits quicker data exchanges among the cores, which improves performance in applications that are optimized for multiple cores.

With new processors comes the new X79 chipset, and Socket 2011. Yes, a brand-new socket; the sound you hear is a legion of serial upgraders howling with rage. For them, the new socket means having to spring for new motherboard, but the news it isn't entirely bad. When I met with Intel representatives, I was assured that the performance-oriented Socket 2011 will be with us for a few years -- at least until an Extreme Edition of the 22-nanometer Ivy Bridge architecture makes the rounds.

For the frugal enthusiast, picking up a Core i7-3820 CPU is an intriguing option. That CPU is likely to be priced competitively with the existing Core i7-2600K--in the neighborhood of $300. Grab one of them when they're available, save your pennies, and you'll be ready to dive into whatever 22nm-based Extreme Edition goodness Intel comes up with a year from now.

What's New?

Intel parked its test Core i7-3960X CPU on a DX79SI "Siler" motherboard. The Siler is well equipped, to say the least. Eight DIMM slots offer a potential 64GB of RAM, with four DIMMs arranged on each side of the processor. This could pose a problem for some larger CPU fans. For my tests Intel provided an Asetek liquid cooling kit, but plenty of alternative cooling systems and motherboards supporting Socket 2011 will undoubtedly be available at or near launch.

The X79 chipset.
Two USB 3.0 ports occupy the rear of the motherboard, with onboard connectors providing another pair for your case. The Siler supports a total of 14 USB ports--six on the rear, and eight on three onboard headers--with room for two FireWire ports as well. The available SATA channels are fairly standard: two 6.0GB/s SATA ports, four 3.0GB/s SATA ports.

For expansion the motherboard offers three PCI Express 3.0 x16 connectors for triple-SLI and Crossfire graphics card configurations, plus a few PCI Express and PCI connectors. The board also provides dual gigabit ethernet jacks, and an IR transmitter/receiver.

Turbo Boost returns, with some improvements. This is how it works: Processors have heat and power thresholds beyond which they become unstable and shut down, or worse. But since processors don't always hit the peak of their thermal design power (TDP), there is some headroom for overclocking.

Turbo Boost (and AMD's variant, dubbed Turbo Core) take advantage of that performance gap, boosting the performance of the operating cores until the TDP is reached, or until the task at hand is done. In the Core i7-3960X, Turbo Boost means a bump of 300MHz per core when five to six cores are active, and a bump of 600MHz per core when only one or two cores are active.

I paired the Core i7-3960X with the Radeon HD 6990 graphics card, 8GB of RAM, and a 1TB hard drive. To get an idea of where SandyBridge E sits in the grand scheme of things, I tested it against the 3.46GHz Core i7-990X, last year's Extreme Edition processor. For mere mortals there's the 3.4GHz Core i7-2600K, the cream of the current Sandy Bridge crop. With the exception of their motherboards our testbeds were identical, and all tests were performed on systems attached to a 30-inch display.

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