Intel's Core i7-3960X is fast, but will break your bank

Review: Undoubtedly the quickest CPU to date, but will you even notice? Intel's new 3960X is almost too fast for its own good.

When Intel launched its enthusiast Nehalem architecture processors, codenamed Bloomfield, alongside Socket 1366 way back in 2008 it marked a significant departure from the way in which the company had historically managed its Extreme Edition processors. No longer would they share a socket with the mainstream; instead the high end enthusiast lineup would have its own, fancier platform.

Thanks to follow-up Westmere CPUs like Intel’s Core i7-980X and -990X, the LGA 1366 platform and accompanying X58 chipset have had a long and fruitful life. But like all good things they are now obsolete, replaced by the new flavour of Extreme, the Core i7-3960X. Known as Sandy Bridge-E, this new CPU takes on all the hallmarks of an Extreme edition. Priced around $1250 (which doesn’t even include a cooler), it is the fastest CPU in Intel’s lineup and has support for a bunch of exotic features.

For the 3960X Intel has taken its upcoming Xeon design, and locked off two of the cores. This leaves six cores running at a non-turbo frequency of 3.3GHz, spiking up to 3.9GHz. It also means that the processor has a quad channel memory controller, 15MB of L3 cache and theoretical support for PCI-Express 3.0.

It is also more overclocker-friendly than standard Sandy Bridge processors. With the Sandy Bridge architecture Intel linked all of the internal speeds to a single clock generator in the CPU. This meant the end of bus-based overclocking for the standard processor lineup, with end users being relegated to playing with the multiplier on the unlocked -K variants of Sandy Bridge.

[subhead] What’s new

With Sandy Bridge-E Intel has added limited ability to overclock the CPU via the bus. This isn’t the kind of granular speed control that the FSB or QPI offered; rather the bus can be switched between preset levels of 100MHz, 125MHz, 166MHz and 250MHz. This new speed only applies to the signal being sent to the CPU, and it is still somewhat inflexible considering what has been possible in the past.

These new features all sound pretty impressive, but the reality is that Sandy Bridge-E is less important than Bloomfield was when it launched. Bloomfield predated the normal desktop versions of the Core series processors, which enhanced its position as the go-to performance solution. This time around, Sandy Bridge-E has arrived almost a year after the mainstream Sandy Bridge processors, which deliver more than enough performance for the majority of PC owners.

Where Sandy Bridge-E shows value is in specific areas and for specific usage models. This is much more of a workstation platform than one for gaming or light use. The extra memory bandwidth provided by the quad-channel memory controller, as well as a prevalence of motherboards with eight DIMM slots, mean those undertaking memory-hungry workloads will love what the 3960X brings to the table.

As will those with serious SLI or Crossfire addictions. The PCI-Express controller has 40 lanes directly to the CPU which allows for two graphics cards to be used with full x16 connectivity, or four cards with x8. This is without the need for third party PCI-E bridges getting in the way, which makes activities like overclocking a lot smoother as well as maximising multi-GPU bandwidth.

The PCI-Express controller also technically supports PCI-Express 3, although Intel has been quite vocal in stating that it won’t officially support the new interconnect version without graphics cards to test it with. This very lack of graphics cards indicates that PCI-Express 3 is still some years away from being a must-have, so while support is nice, it is by no means a selling point.

While there are certainly interesting new technologies within the Sandy Bridge-E architecture, the same cannot be said of the accompanying chipset, the X79. This has virtually the same feature-set seen on the mainstream P67, with no native USB 3 support and a measly two SATA 6Gbps ports. At Computex we saw X79 motherboards with support for Serial Attached SCSI drives, however these are now nowhere to be seen, despite the RAID controller coming from a family that supports SAS (you need to use Intel’s enterprise driver to configure them anyway, so why not support an enterprise SAS feature?).