Intel started slowly leaking information about an ultra high-end enthusiast platform dubbed Skulltrail at right about the same time that AMD’s now defunct QuadFX platform was set to be released. Over time we learned that Skulltrail, like QuadFX, would be a dual-socket platform that could accommodate a pair of Intel’s fastest quad-core processors, for a grand total of eight execution cores in one desktop system. But other details regarding the platform were somewhat scarce to say the least.As time progressed, however, Intel was more and more forthright with information regarding Skulltrail. Soon we learned that the platform would require DDR2 FB-DIMMs and that it would officially support a 1600MHz front side bus frequency. Then later Intel disclosed that Skulltrail would support not only ATI’s CrossFire multi-GPU technology, but NVIDIA’s SLI as well. Then at IDF last year we were treated to our first glimpse of a fully assembled Skulltrail system that featured dual 3.2GHz quad-core processors and were even privy to some preliminary benchmark results. And finally, at this year’s Consumer Electronics Show, Intel showed off a couple of Skulltrail-based rigs complete with air and water-cooled processors running at a cool 4GHz. At this point we knew Skulltrail was almost ready for prime time.
After meeting with Intel at CES, representatives informed us that Skulltrail would be available for testing and evaluation in just a few weeks. And they were true to their word. We’ve been banging on a Skulltrail setup complete with a matched pair of 3.2GHz Core 2 Extreme QX9775 processors and DDR2-800 FB-DIMMs for a couple of weeks now and will be presenting the results of our testing for you all right here. Strap yourself in and prepare for the eventual feelings of CPU envy that will ensue. Skulltrail is a beast in every sense of the word...
Specifications and Features
Our Intel V8 coverage will give you a glimpse into some of the technologies employed in Skulltrail, in workstation-class trim. And our coverage from IDF and CES will give you an idea as to how the Skulltrail platform has matured while Intel was readying the platform for release.
Intel’s Skulltrail platform borrows heavily from its workstation-class roots. At its core, Skulltrail is based on the Intel 5400 series chipset, but the D5400XS motherboard that is the foundation of Skulltrail also features a host of additional customizations that set it apart from Intel’s typical workstation-class motherboards.
This high-level block diagram illustrates exactly what the D5400XS motherboard has to offer and hints at a few of its enthusiast oriented features. As you can see, the Intel 5400 MCH (Northbridge) is linked to a pair of a LGA771 processor sockets. These sockets support standard Xeon processors in addition to the high-end Core 2 Extreme QX9775.
The Intel 5400 MCH in this configuration offers four Fully Buffered DIMM (FBDIMM) memory channels. The MCH's four memory channels are organized in to two branches and each branch is supported by a separate memory controller. The two channels on each branch operate in lock step to increase FBD bandwidth. This may lead you to believe that the platform requires four DIMMs to operate at full performance, but representatives from Intel have informed us that only synthetic memory benchmarks benefit from utilizing four memory channels and that in real-world situations a pair of DIMMs will perform just as well.
Also linked to the 5400 MCH is a pair of NVIDIA nForce-100 PCI Express 1.1 switches. These switches take 32 PCI Express lanes from the MCH and fan them out to four PEG slots. These nForce switches give the Intel D5400XS motherboard the ability to support NVIDIA’s SLI multi-GPU technology, and the chipset itself supports CrossFire. This setup makes the D5400XS the only motherboard available that officially supports both multi-GPU technologies. We should note, however, that the D5400 XS will only support 2-way SLI as per a recent conversation with NVIDIA. It does support up to four-way CrossFireX though.
Hanging off of the MCH is the Intel 6321ESB I/O Controller Hub, or Southbridge. The 6321ESB I/O Controller Hub gives the platform support for SATA and PATA with RAID, USB 2.0 and High Definition audio, among other things. The Southbridge on the D5400XS is also supported by Firewire controller and a Marvell SATA controller that powers a pair of eSATA ports in the motherboard’s I/O backplane.
With our Skulltrail system assembled, we fired up the latest version of CPU-Z to give you all a glimpse into the platform’s inner workings. As you can see, in its stock configuration the Core 2 Extreme QX9775 processors powering the platform are clocked at 3.2GHz (8 x 400MHz) with a 1.25v core voltage. The processor technology is correctly identified as 45nm and the processors use Intel’s Socket 771 LGA packaging. In essence, the QX9775 processors are identical to the QX9770 we recently tested, just in a different package (LGA771 vs. LGA775). The processor cache and memory configuration are also available above, as are a few details regarding the motherboard and its BIOS configuration.
There are a lot of subtle details that hint at the Intel D5400XS motherboard’s enthusiast-class nature. The first thing we want to point out is that although the motherboard supports Intel’s LGA771 Xeon processors, the sockets are configured to accept LGA775 heatsinks and coolers. If you’ve ever shopped for LGA771 coolers, you’ll know that it is much more difficult to find quiet, yet powerful LGA771 coolers, but with this motherboard that problem has been eliminated.
Early iterations of Skulltrail featured basic heatsinks on the motherboard’s chipset and PCI Express switches, but the D5400XS that will eventually be for sale features a single large heatsink on the MCH and a wide, flat active cooler that links the Southbridge and nForce 100 chips. This cooler and its associated shroud are definitely two of this motherboard’s flaws. Throughout testing we found the Southbridge cooler’s fan to be excessively loud and the shroud was held in place with double-stick tape that gave way and popped off a couple of days into testing. Unless we got a bum sample, we can’t see the shroud’s double-stick tape holding up in a warm enclosure over an extended period of time, so do yourself a favor and remove it if you should be one of the lucky few who end up buying a D5400XS.
The D5400XS conforms to the EATX form factor, so it will require a compatible chassis. Despite the board’s elaborate feature set, overall its layout is surprisingly good. All of its major connectors and headers are situated around the edges of the board, and they are all clearly labeled and easy to identify. The DIMM slots are located right in the middle of the board, which is a departure from most enthusiast class motherboards, but the positioning works well and obviously doesn’t interfere with any expansion cards. An important note regarding the memory, however, is that the DDR2-800 FB-DIMMs we tested got incredibly hot during normal use. In fact, according to our trusty infrared thermometer, the memory’s outer heatspreader hit a sizzling 63ºC, which means the ICs underneath were no doubt even hotter. It would be a good idea to invest in an active memory cooler if a Skulltrail platform is in your future; although we have to point out we experienced no heat related instability throughout our testing and evaluation.
As for the board’s I/O configuration, it has six internal SATA ports, a single IDE port, and headers for additional USB and Firewire ports. On the I/O backplane, there are no legacy connectors to be found, but it does have six USB ports, dual eSATA ports, single Firewire and Gigabit Ethernet jacks, and analog and digital HD audio inputs / outputs.
While we’re showing off Intel’s extreme flagship motherboard, we also wanted to give Skulltrail’s cousin a bit of exposure. The motherboard you see pictured here is Intel’s DX38BT, which was codenamed Bonetrail during development. As its name implies, the DX38BT board is based on Intel’s X38 express chipset and as such it supports all current Core 2 processors with front side bus speeds up to 1333MHz. An X48 variant is also in the works that will officially support processors with FSB speeds up to 1600MHz. The DX38BT also supports DDR3 memory and has a full set of overclocking controls available via its system BIOS and through Intel’s Desktop Control Center software.
As you can see, the DX38BT also has nearly the exact same I/O port configuration as the D5400XS in its backplane. Like the D5400XS, the DX38BT has dual eSATA ports, single Firewire and Gigabit Ethernet jacks, and analog and digital HD audio inputs / outputs. The DX38BT, however, features eight USB 2.0 ports here, instead of Skulltrail's six.
Mostly blue and white connectors are spread out nicely around the board. leaving a mostly clean layout. Two blue PCI-E x16 slots with ample space between them populate the upper area, interspersed with 2 white PCI and 2 white PCI Express x1 slots. The SupremeFX II audio riser card is parked in its own black colored PCI Express x1 slot with a fan header close by, nestled in tightly inside a bend in the heatpipes. LEDs are placed strategically around the board, and are used to display the voltage status for CPU, Northbridge, Southbridge and memory in an intuitive color-coded fashion (read: green = good, red = bad).Front Panel pins are placed in the closest corner to the front of the unit, followed by 2 sets of USB 2.0 headers, the on-board power and reset buttons that we've come to know and love, and then a Firewire header. Forward angled SATA ports provide the ability to attach six SATA drives, and another forward angled IDE port controlled by the JMicron controller can be used for installing two more IDE devices. Floppy drives can still call the Rampage Formula home as a port lies near the 20-pin power plug. The board's color coded DIMM slots have power regulation circuitry right next to them and there's just enough room between the clips on the DIMM slots and the graphics card so that they won't come into contact.
With all of the information AMD has already revealed regarding the Phenom II's overclockability, we were eager to see what our particular chip could do. We didn't use any exotic cooling for our overclocking experiments, opting instead to see just how far the chip would go with a stock AMD PIB air cooler installed. With only a minor bump in voltage to 1.575v, we were able to take our particular CPU to almost 3.8GHz using the stock air cooler alone. That speed was achieved with an 18.5x multiplier and a 202MHz base clock; the components were installed in a basic mid-tower. The AMD Overdrive utility shown in the screenshot above did not report clock speeds correctly, but assuming thermal readings were correct (we don't think they were), the chip ran at about 50'C while overclocked. 
Running a complex DirectX 9 pixel shader, rich in math1ematical calculations, the new graphics core from Intel finds itself behind the GeForce FX 5200, not even mentioning the RADEON 9600/9550.
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