The products: the Core i7-3000 series
Intel has plans for a trio of CPUs in the Core i7-3000 series, two of which are hitting the market today. The one we have for review is the top dawg, the Core i7-3960X, with the beefiest specs in the table above and a hefty price tag of $990 to match. Like other Extreme products from Intel, the 3960X has unlocked multipliers to ease overclocking.
As we've noted, the 3960X has portions of the die disabled, namely two of the CPU cores and 5MB of L3 cache. Releasing a top-of-the-line desktop chip with portions disabled runs contrary to our expectations, but we think Intel had some cogent reasons for making this choice. That is, in order to reach the same 3.9GHz peak Turbo Boost frequency as the top Sandy Bridge quad-core product while staying within the 130W power limit, a couple of cores had to be sacrificed. For a desktop-oriented product where performance in lightly threaded applications remains very important, we can see the logic of this tradeoff. After all, it wouldn't do for the 3960X to be measurably slower than the Core i7-2700K in a number of applications.
The flip side is that it's difficult to imagine the typical person who's willing to shell out nearly a grand for a high-end processor being happy in the knowledge that substantial portions of his new chip have been disabled. We also can't help but notice that the 3960X is nine bucks short of Intel's usual $999 price tag for an Extreme Edition product. A true eight-core part would sure slot in neatly at $999 at some point down the line, don't you think?
Since the table above doesn't show it, we should relay the exact Turbo Boost behavior you can expect from the 3960X. The top frequency of 3.9GHz can be reached when only one or two cores are active. With three to four cores active, the chip drops down to 3.7GHz, and with five to six cores active, the clock dips to 3.6GHz. Like most Sandy Bridge-based CPUs with Turbo Boost, we've not seen the 3960X spend any time at its 3.3GHz base frequency. When none of the cores are busy, the processor settles at 1.2GHz via SpeedStep or the C1E halt function.
Of course, the 3960X is practically superfluous given the specs and price of the next model down the line, the $555 Core i7-3930K. The 3930K gives up 100MHz in base and peak clock speeds and has 3MB less L3 cache than the 3960X, but as a K-series part, it also is unlocked and ready to overclock. Pretty much no one should pay the premium for the 3960X when the 3930K will sell for $555, practically a bargain in the rarefied air of Extreme-class processors. We had hopes of reviewing the 3930K processor today, but Intel wasn't providing advance samples of this product to reviewers. We'll have to snag one later.
If you really like the idea of the Sandy Bridge-E platform but aren't ready to pony up the big bucks as the price of entry, Intel may have a more appealing option for you in the first quarter of 2012: the Core i7-3820. With four cores and a 3.9GHz Turbo peak, the 3820 looks poised to follow in the footsteps of past enthusiast favorites like the Core i7-920, which offered reasonably priced access to the X58 platform a few years back. We don't yet know the exact pricing of the 3820, but we'd expect it to slot between the options above and below it in the table, hopefully somewhere south of the $400 mark. Intriguingly, Intel plans to produce a native quad-core variant of Sandy Bridge-E, so the 3820 may not just be a larger chip with portions disabled.
The final product we'll call out from the table above is the Core i7-2700K, a non-Extreme Sandy Bridge part that recently took its place at the top of Intel's mid-range lineup. The 2700K is only 100MHz faster than the previous champ in that segment, the 2600K, so it's nothing to write home about. Still, we were intrigued about how it would stack up against the 3960X, so we've included performance results for it in the following pages.
A new chipset: the X79 Express
Although Sandy Bridge-E integrates a boatload of high-bandwidth connectivity, it still needs a support I/O chip to handle various lower-speed I/O types. That chip is known as the X79 Express. As you may have noticed while peering at the block diagram above, the X79 looks very much like the P67 support chip used in the mid-range Sandy Bridge platform.
Most of what you'd want in a core-logic chipset is included, with only a couple of exceptions. For one, the USB ports don't support the new SuperSpeed or 3.0 standard; motherboard makers will have to add that feature via a third-party USB controller chip. Also, only two of the six SATA ports can achieve 6Gbps transfer rates; the rest top out at 3Gbps. That may not seem like a horrible limitation given that only SSDs can really make full use of 6Gbps interfaces; putting a mechanical drive on a 6Gbps interface won't get you much. Still, the X79's collection of six SATA ports may seem kind of skimpy given the other specifications of this platform. In fact, Intel built another SAS/SATA disk controller into the X79, along with an additional PCIe x4 interconnect to the CPU, in order to provide more fast disk I/O capability. Unfortunately, those two features had to be disabled in this version of the X79 for "silicon health reasons." We expect a future revision of this chip will restore that functionality, probably when it's deployed in dual-socket servers.
Another casualty of the X79's apparent rush to market is the Smart Response scheme that lets a small, fast solid-state disk act as a cache for a larger mechanical hard drive. This feature debuted in the Z68 chipset for Sandy Bridge processors, but the X79 ships without it. Intel intends to add Smart Response caching to the X79 via a future driver update, but its timeframe for doing so is quite a ways off: by mid-2012.