The best price we could find for the twin 2GB sticks Intel supplied with the Skulltrail review kit was £600. Of course, the peak bandwidth figure will require each of Skulltrail's four memory slots to be populated, the potential cost of which really doesn't bear thinking about.
The pros and cons of Stoakley aside, there are a number of important areas where Skulltrail differs from a conventional 5400 series motherboard. The really big change is the addition of a pair of Nvidia nForce 100 MCP PCI Express bridge chips.
On the downside, that means a downgrade from the standard PCI Express 2.0 support of the 5400 chipset to the slower PCI Express 1.1 interconnect specification. However, the twin MCP chips deliver two important features. The first is support for NVIDIA's SLI multi-card 3D graphics technology, a capability that has previously been reserved for full NVIDIA chipsets.
The second is enough PCI Express lanes to support no less than four PCIE graphics ports, each with 16 lanes. In turn, that means Skulltrail has the gumption to support four video cards in quad-SLI mode. For now, that's a theoretical feature. Nvidia has not released a driver that supports more than three cards in SLI mode.
Built for overclocking
Just as important for enthusiasts are the overclocking features Intel has added. Most obviously, the QX9775 processors receive unlocked CPU multipliers. That allows for increased frequencies without stressing the motherboard chipset or memory DIMMs.
But if Skulltrail does have a weakness, it's the data bandwidth to those cores. Intel has therefore kitted out the D5400XS's BIOS with a full range of overclocking options.
Both frequencies and voltages for the northbridge and memory are fully adjustable. Memory latency fine tuning is also possible thanks to a full set of timing options. In short, it's every bit as tweakable as an conventional Intel desktop board based on chipsets such the the P35 and X48.
The only slight downside is the need for both CPUs to run at the same speed. Consequently, the maximum overclock is defined by the weaker of the two chips. That said, independent voltage adjustments are available for each CPU.
Unfortunately, however, Skulltrail's physical properties are not quite as enthusiast-friendly as its overclocking features. The EATX form factor of the D5400XS motherboard is much deeper than a standard ATX motherboard. It won't fit in most desktop cases.
As fast as a supercomputer
Nevertheless, with the right case and PSU, Skulltrail certainly adds up to a mountainous machine for desktop computing. With eight 3.2GHz processor cores, 24MB of cache memory and perhaps as many as four GPUs, on paper Skulltrail packs as much compute power as the fastest early 1990s supercomputers.
But how does it perform in the real world in 2008? The key question, in other words, is whether today's applications are capable of taking advantage of eight CPU cores? With the debate that still rages over the merits of quad-core processors, is the desktop really ready for eight-core computing?
The simple answer is that it depends on the application. The raw performance of the platform is amply demonstrated by synthetic tests such as SiSoft Sandra where Skulltrail is very nearly twice as quick as the fastest single-socket desktop processor, the Core 2 Extreme QX9770 3.2GHz chip.
Likewise, applications capable of generating fully eight CPU-intensive software threads absolutely fly. Both our X.264 video encoding and Cinebench 3D rending benchmarks run over 50 per cent faster on Skulltrail than a system based on a single QX9770 CPU.
No real-world benefit from eight cores?
However, when it come to programs that are unable to generate the full compliment of eight software threads, whether single or multi-threaded, Skulltrail is much less impressive. As far as we are aware, for instance, there isn't a single PC game that can spread itself over eight cores.
Even high-tech titles that scale very well on quad-core processors such as Half-Life 2 and Crysis derive no benefit at all from another eight cores.
In fact, probably thanks to the overheads of a more complex platform and the slower memory subsystem, confirmed by our bandwidth benchmark, such software actually runs significantly slower on Skulltrail. Granted, performance is still strong in isolation.
But with the enormous cost of Skulltrail, buyers would be justified in demanding the best performance in all scenarios.
In the end, Skulltrail's prohibitive pricing is impossible to ignore. The two CPUs, motherboard and memory alone will set you back well over £2,000. Even for those who aren't worried by that terrifying figure, the fact that Skulltrail does not deliver total performance dominance should be enough to make them think twice.
Finally, here's a thought for Intel to consider regarding an alternative route to extreme desktop performance. Given the enormous overclocking headroom of the latest 45nm Core 2 processors, it's abundantly obvious that a low volume 4GHz model is possible.
Wouldn't that be a simpler, more realistically-priced solution with more consistent performance?
