When Intel launched its "Sandy Bridge" second-generation Core processors in January year, it launched only "mainstream" parts, with prices ranging from about $64 for Pentium-branded processors, up to about $340 for the latest Core i7-2700K. Fast as they were, the high-end enthusiast processors were stuck on the previous generation Nehalem architecture. No longer: Sandy Bridge E is here.

Original Sandy Bridge processors have up to four cores, up to eight threads, 8 MiB cache, two memory channels, an integrated GPU, and PCIe 2.0. The cores themselves haven't changed for Sandy Bridge E, but there are more of them, and their supporting infrastructure has seen a hefty update: Sandy Bridge E processors have up to six cores, up to 12 threads, up to 15 MiB cache, four memory channels, no integrated GPU, and PCIe 3.0. The only thing not changed is clock speeds: the $990 top end Core i7 3960X (6 cores, 12 threads, 15 MiB cache) has a base clock of 3.3 GHz, with a maximum of 3.9 GHz, comparable to the 3.5/3.9 GHz of the Core i7 2700K.

Also launching today is the $555 Core i7 3930K; 6 cores, 12 threads, 12 MiB cache, 3.2/3.8 GHz. Next year, Intel will release a 4-core, 8-thread Core i7 3820, with clock speeds of 3.6/3.9 GHz and 10 MiB cache. Pricing for that is expected to be around $300. All the Sandy Bridge E processors have a 130 W power rating, compared to 95 W for the highest-end mainstream Sandy Bridges.

With the new chips comes a new socket—Socket 2011—and a new chipset, though again this will seem awfully familiar. Sandy Bridge E is paired with the X79 chipset, which offers a specification that's all but identical to Sandy Bridge's P67 chipset. Intel initially planned to give X79 an all-new I/O controller named SCU that would include support for both SATA and Serial Attached SCSI (SAS). Intel had unspecified problems with this, so X79 offers the same combination of two 6 Gbps plus four 3 Gbps SATA connections.

The two 6-core processors available now are both overclockable, with unrestricted clock multipliers. The four-core processor will be more restricted. In an unusual move, the Sandy Bridge E processors don't include a fan/heatsink unit, even when bought in retail packaging. Instead, Intel is selling two separate cooling solutions. One is a traditional cheap fan and heatsink that looks similar to the one currently used on retail Sandy Bridge processors. The other is a sealed water cooling system with a water block, radiator, and fan, mirroring AMD's decision to ship a similar water cooling unit for Bulldozer. Serious overclockers will likely want something with more bulk and heat dissipation power, but as an introduction to water-cooled overclocking Intel's solution may find its fans.

The performance of Sandy Bridge E is much as would be expected: per Anand and Tech Report, it's slightly faster for single-threaded applications (thanks to that huge cache) and about 50 percent faster for multithreaded applications (thanks to having 50 percent more threads) than Sandy Bridge.

The price and performance mean that Sandy Bridge E will likely be of only limited appeal. Most of the high-end desktop market is already satisfied by the cheaper four core, eight thread i7 2600 and i7 2700 models. Only those who simply must have the fastest single socket processor around will have any interest in Sandy Bridge E. Fast as it is, the market Intel is aiming at just isn't that big, and as the mid-range processors become ever more capable, is set to decline further.

Sandy Bridge desktop processors have corresponding Xeon parts, the Xeon E3 series. Sandy Bridge E will gain similar counterparts, but they're not releasing just yet. That's because Sandy Bridge E has a bug in its virtualization hardware, forcing Intel to disable VT-d I/O virtualization (though VT-x CPU virtualization still works). Intel regards that as tolerable for the desktop processors—the existing "K" series Sandy Bridge processors already have VT-d disabled—but not for server workloads, where VT-d is required to perform direct assignment of network interfaces to virtual machines.

Update: Intel's Ark site was updated after publication to include the new processors and it says that they do in fact support VT-d, which means that Intel has managed to get the (fixed) C2 stepping out in time after all.

When the problem is fixed and the Xeon processors do start to ship in the first quarter next year, they'll pack even more punch than the desktop parts. The Sandy Bridge E desktop parts may have six cores and up to 15 MiB cache, but the die itself has eight cores and 20 MiB cache (and with 2.2 billion transistors, is even larger than AMD's 2 billion transistor Bulldozer die). Some of those cores and cache are disabled for the desktop processors. For the server-oriented Xeon processors, they'll all be enabled. The Xeon parts are due to ship with the Xeon E5 branding, and model numbers from 2603 to 2690.