SkulltraiI: Intel's 8-core supercomputer

The wraps are off Intel's latest eight-core desktop computing platform. Known as Skulltrail, it isn't Intel's first dual-socket technology designed for desktop. But it is much more polished than before and brings what Intel reckons to be supercomputing performance to the desktop.

Skulltrail is intended to be a crushing display of technical superiority by Intel. The dual CPU sockets are filled with a pair of Core 2 Extreme QX9975 processors. Each chip packs four cores running at 3.2GHz, the same frequency as Intel's top single-socket desktop CPU, the QX9770.

Indeed, in terms of processor technology, there's little to separate the new dual-socket kit from Intel's existing single-socket clobber. With bus speeds of 1,600MHz, power efficient 45nm production technology and a slightly silly 12MB of cache memory, that's hardly a problem.

The only area where the new chips differ is socket specification. Instead of Intel's LGA775 interface, the QX9775 requires the LGA771 socket as seen on Xeon workstation and server platforms.

That's a highly revealing alteration, because the new chipset that underpins Skulltrail is actually a mildly tweaked version of the 5400 series server chipset. Revised for this new desktop implementation, it receives the D5400XS moniker.

Bags of bandwidth

For the most part, little has changed. On the upside, that means dual independent 1,600MHz processor buses and bags of data bandwidth. Less welcome is the need for fully buffered (FB) memory DIMMs. They're more expensive, run hotter but slower (800MHz DDR2) and suffer from relatively tardy timings compared with conventional unbuffered desktop DIMMs.

One big difference is the addition of a pair of NVIDIA nForce 100 PCI Express signalling chips. The result is theoretical support for up to four NVIDIA GPUs running in SLI multi-rendering mode. In practice, support is limited to three cards at launch. Intel has also added a full range of enthusiast-friendly overclocking options to the D5400XS's BIOS.

As for pricing, well, it you have to ask you're not going to like the answer. Expect to fork out at least £700 per CPU, plus another £250 for the motherboard. Oh, and the minimum 4GB of 800MHz DDR2 FB-DIMMs you will probably want? That'll be another £500 or more. Nice.

So, how does this enormously powerful and painfully pricey kit perform? In terms of raw compute power, Skulltrail is equivalent to a mid 90s supercomputer.

Suffice to say that for multi-threaded software and multi-tasking, nothing else comes close. However, it's not all good news. Single-threaded performance is slightly down compared to Intel's single-socket platforms. And the server origins of the 5400 chipset appear to scupper its overclocking capabilities.


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