Intel Skulltrail Unleashed: Core 2 Extreme QX9775 x 2

Skulltrail High-Level Overview

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.


Intel Core 2 Extreme QX9775 and D5400XS CPU-Z Information

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.

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