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Intel Skulltrail Unleashed: Core 2 Extreme QX9775 x 2
Date: Feb 16, 2008
Author: Marco Chiappetta
Introduction, Specs, and Related Info


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...

Intel Skulltrail D5400XS Motherboard

Intel Skulltrail D5400XS
Specifications and Features

We have posted a myriad of information related to the Skulltrail platform in recent articles here at HotHardware.  If you’d like more details regarding Intel’s Core 2 micro-architecture or want to see all of the early information regarding Skulltrail that we have posted in the past, we recommend perusing these articles:

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.

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.

Skulltrail and Bonetrail Motherboards

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.



The D5400XS motherboard also features an on-board POST code error reporter and handy integrated power and reset switches – at least they’re handy for people like us who have to test a ton of hardware.    The motherboard’s expansion slots consist of a quartet of PCI Express X16 slots, that all feature X16 electrical connections thanks to the dual nForce 100 switches, and a pair of standard PCI slots.

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.

Skulltrail BIOS and Overclocking

Unlike Intel-built motherboards from years past, the Skulltrail D5400XS has very complete and relatively easy to navigate BIOS geared for enthusiasts. From within the BIOS users have the ability to configure, enable or disable all of the board's integrated peripherals, and monitor voltages, temperatures, fan speeds,  and clock speeds. The D5400XS also has a relatively complete set of memory timing options that offer some flexibility for fine tuning memory performance.

Intel D5400XS - The BIOS
It's All Right Here



The DX5400XS’ standard BIOS menu screens don't reveal anything out of the ordinary, but they will give you a feel for the general layout and organization of the options.  Each individual screen has a host of menus that tunnel deeper and deeper as the options get more complex.

Other than the color scheme and naming conventions, the D5400XS’ menus are very similar to the Award and AMI BIOS derivatives used on most other high-end motherboards being manufactured today, but navigating through Intel's  BIOS menus may take some getting used to if you've never experienced them before.

Intel D5400XS - Overclocking
It'll Do


It’s within the Processor, Bus, and Memory Override sections of the DX5400XS’ BIOS that you'll find most of the board's performance and overclocking related tuning options.  From within these sections of the BIOS, users have the ability to alter clock frequencies and voltages for virtually every major on-board component. The CPU and PCI Express frequencies can be altered in 1MHz increments, and the CPU multiplier and memory ratio can also be manipulated manually.  There are also extensive voltage options for the CPU, Memory, and chipset, with helpful information available in the right-most column that explains what many of the options do.

Skulltrail Overclocked to 4GHz

After seeing Intel’s 4GHz Skulltrail rigs at CES, we were eager to see what our samples could do with a little cajoling.  With each CPU outfitted with a Zalman CNPS9500 copper cooler, we increased their core voltage to 1.35v (+.1v), and raised the CPU multiplier until our test setup was no longer stable.  In the end, we were able to hit a stable 4GHz with very little effort.  We’re sure some of you may be wondering what the motherboard could do with a standard Xeon processor in its socket, but unfortunately we were not able to test this just yet.  And Intel wasn’t clear on whether or not they would allow FSB overclocking on Xeons that already feature a high 1600MHz FSB frequency.

Our Test Systems and SANDRA

How we configured our test systems: When configuring our test systems for this article, we first entered their respective system BIOSes and set each board to its "Optimized" or "High performance Defaults". We then saved the settings, re-entered the BIOS and set memory timings for either DDR2-1066 (AMD) with 5,5,5,15 timings, DDR3-1333 - 1600 with 7,7,7,20 timings (Intel), or DDR2-800 5-5-5-15 (Skulltrail). The hard drives were then formatted, and Windows Vista Ultimate was installed. When the Windows installation was complete, we updated the OS, and installed the drivers necessary for our components. Auto-Updating and Windows Defender were then disabled and we installed all of our benchmarking software, defragged the hard drives, and ran all of the tests.

 HotHardware's Test Systems
 Intel and AMD - Head To Head 

System 1:
Core 2 Extreme QX9775
(3.2GHz - Quad-Core)

Intel D5400XS
(5400 Series Chipset)

2 x 2GB Micron FBDIMM
CL 5-5-5 - DDR2-800

GeForce 8800 GTX
On-Board Ethernet
On-board Audio

WD740 "Raptor" HD
10,000 RPM SATA

Windows Vista Ultimate
Intel INF
NVIDIA Forceware 169.28

System 2:
Core 2 Extreme QX9770
(3.2GHz - Quad-Core)
Core 2 Extreme QX9650
(3.0GHz - Quad-Core)
Core 2 Quad Q6600
(2.4GHz - Quad-Core)

Asus P5E3 Deluxe
(X38 Chipset)

4 x 1GB Corsair DDR3-1800
CL 7-7-7 - DDR3-1333/1600

GeForce 8800 GTX
On-Board Ethernet
On-board Audio

WD740 "Raptor" HD
10,000 RPM SATA

Windows Vista Ultimate
Intel INF
NVIDIA Forceware 169.28

System 3:
AMD Phenom 9700
AMD Phenom 9600
AMD Athlon X2 6400+

Gigabyte gA-MA790FX-DQ6
(AMD 790FX Chipset)

4 x 1GB Corsair PC2-8500
CL 5-5-5-15 - DDR2-1066

GeForce 8800 GTX
On-Board Ethernet
On-board Audio

WD740 "Raptor" HD
10,000 RPM SATA

Windows Vista Ultimate
NVIDIA Forceware 169.28

System 4:
AMD Athlon 64 FX-74
(3.0GHz x 2)

Asus L1N64-SLI WS
(nForce 680a SLI)

4 x 1GB Corsair PC2-6400
CL 4-4-4-12 - DDR2-800

GeForce 8800 GTX
On-Board Ethernet
On-board Audio

WD740 "Raptor" HD
10,000 RPM SATA

Windows Vista Ultimate
nForce Drivers v15.08
NVIDIA Forceware 169.28

 Preliminary Testing with SiSoft SANDRA XII
 Synthetic Benchmarks

We began our testing with SiSoftware's SANDRA XII, the System ANalyzer, Diagnostic and Reporting Assistant. We ran six of the built-in subsystem tests that partially comprise the SANDRA XII suite on the Skulltrail system (CPU Arithmetic, Multimedia, Multi-Core Efficiency, Memory, Cache, and Memory Latency).  All of the scores reported below were taken with the processors running at their default clock speed of 3.2GHz with DDR2-800 FB-DIMMs.

QX9775 x 2 @ 3.2GHz
CPU Arithmetic

QX9775 x 2 @ 3.2GHz

QX9775 x 2 @ 3.2GHz
Multi-Core Efficiency


QX9775 x 2 @ 3.2GHz
Memory Bandwidth


QX9775 x 2 @ 3.2GHz

Cache and Memory


QX9775 x 2 @ 3.2GHz
Memory Latency

SANDRA's various benchmark results are a mixed bag.  In the processor intensive tests, the Skulltrail rig crushes everything else available in SANDRA's reference database.  The system's eight execution cores and high clock speed give it an obvious advantage over any other system where multi-threaded CPU performance is concerned.  The cache and memory, and multi-core efficiency benhcmarks also paint Skulltrail in a good light, as the system performs at, or near, the top of the charts in those tests as well.  It's in the memory bandwidth and latency tests that the Skulltrail system faulters, however.  In the memory bandwidth test, Skulltrail barely breaks the 7GB/s barrier and it has a somewhat high memory latency rating of 107ns.

PCMark Vantage


For our next round of benchmarks, we ran all of the modules built into Futuremark's PCMark Vantage test suite.  Vantage is a new benchmarking tool that we've incorporated into our arsenal of tests here at HotHardware.  Here's how Futuremark positions their new benchmarking tool:


 Futuremark PCMark Vantage
 Synthetic Benchmarks

"The PCMark Suite is a collection of various single- and multi-threaded CPU, Graphics and HDD test sets with the focus on Windows Vista application tests. Tests have been selected to represent a subset of the individual Windows Vista Consumer scenarios. The PCMark Suite includes CPU, Graphics, Hard Disk Drive (HDD) and a subset of Consumer Suite tests."

The overall PCMark Vantage score is a weighted average of all of the modules in the Vantage suite calculated in total "PCMarks".  Here are the results:


The Skulltrail system and similarly clocked Core 2 Extreme QX9770 perform at similar levels in the overall PCMark Vantage suite.  Only a few pecentage points separate Intel's highest end platforms here, which is to say they beoth perform quite well.



The PCMark Vantage "Memories" suite includes the following tests:

Memories 1 - Two simultaneous threads, CPU image manipulation and HDD picture import
Memories 2 - Two simultaneous threads, GPU image manipulation and HDD video editing
Memories 3 - Video Transcoding: DV to portable device
Memories 4 - Video Transcoding: media server archive to portable device

PCMark Vantage's Memories test mirrors the overall results, with the Skulltrail rig and Core 2 Extreme QX9770 performing within a few pecentage points of each other.


Vantage TV and Movies suite includes the following tests:

TV and Movies 1 - Two simultaneous threads, Video transcoding: HD DVD to media server archive, Video playback: HD DVD w/ additional lower bitrate HD content from HDD, as downloaded from the net
TV and Movies 2 - Two simultaneous threads, Video transcoding: HD DVD to media server archive, Video playback, HD MPEG-2: 19.39 Mbps terrestrial HDTV playback
TV and Movies 3 - HDD Media Center
TV and Movies 4 - Video transcoding: media server archive to portable device, Video playback, HD MPEG-2: 48 Mbps Blu-ray playback


Once again, we see a similar pattern, with Skulltrail just edging out the QX9770.


Courtesy, Futuremark:  "Gaming is one of the most popular forms of entertainment for all ages. Today’s games demand high performance graphics cards and CPUs to avoid delays and sluggish performance while playing. Loading screens in games are yesterday’s news. Streaming data from an HDD in games – such as Alan Wake™ – allows for massive worlds and riveting non-stop action. CPUs with many cores give a performance advantage to gamers in real-time strategy and massively multiplayer games. Gaming Suite includes the following tests: "

Gaming 1 - GPU game test
Gaming 2 - HDD: game HDD
Gaming 3 - Two simultaneous threads, CPU game test, Data decompression: level loading
Gaming 4 - Three simultaneous threads, GPU game test, CPU game test, HDD: game HDD


Vantage's gaming test, which utilizes a maximum of three threads, also performs similarly on Skulltrail and the QX9770, which is to be expected considering both platforms are clocked at the same level and utilized the same supporting hardware (video card and hard drive).

PCMark Vantage (Continued)

We continue our test coverage with a few more modules from the comprehensive PCMark Vantage suite of benchmarks.

 Futuremark PCMark Vantage
 Synthetic Benchmarks

Vantage Music suite includes the following tests:

Music 1 - Three simultaneous threads, Web page rendering – w/ music shop content, Audio transcoding: WAV -> WMA lossless, HDD: Adding music to Windows Media Player
Music 2 - Audio transcoding: WAV -> WMA lossless
Music 3 - Audio transcoding: MP3 -> WMA
Music 4 - Two simultaneous threads, Audio transcoding: WMA -> WMA, HDD: Adding music to Windows Media Player


The Skulltrail system faultered in Vantage's Music benchmark module, presumably due to the platform's memory bandwidth disadvantage versus the DDR3 equipped Core 2 Extreme QX9770.



Vantage Communications suite includes the following tests:

Communications 1 - Three simultaneous threads, Data encryption: CNG AES CBC, Data compression, Web page rendering: graphics content, 1024x768, windowed
Communications 2 - Three simultaneous threads. Web page rendering: open various news pages from IE 7 Favorites in separate tabs, close them one by one, Data decryption: CNG AES CBC, HDD: Windows Defender
Communications 3 - Windows Mail: Search
Communications 4  - Two simultaneous threads, Data encryption: CNG AES CBC, Audio transcoding: WMA -> WMA - to simulate VOIP

PCMark Vantage's Communication test suite proved to be somewhat of a strong point for the Skulltrail system.  In this test, the Skulltrail system finished over 150 points ahead of the next fastest system.


Vantage Productivity suite includes the following tests:

Productivity 1 - Two simultaneous threads, Text editing, HDD: application loading
Productivity 2 - Two simultaneous threads, Windows Contacts: search, HDD: Windows Defender
Productivity 3 - HDD: Windows Vista start-up
Productivity 4 - Three simultaneous threads, Windows Contacts: search, Windows Mail: Run Message Rules, Web page rendering: simultaneously open various pages from IE7 Favorites in separate tabs, close them one by one

PCMark Vantage's Productivity test suite reported similar scores for the QX9770 and Skulltrail system, with the Core 2 Extreme QX9650 finishing not too far behind.  The moral of the PCMark Vantage story?  If four or fewer threads are used, an eight core system is going to perform much like a four core system with similar clock speeds.  As you'll see later, this is not the case with true multi-threaded applications.

Cinebench R10 and POV-Ray

Cinebench R10 is an OpenGL 3D rendering performance test based on Cinema 4D. Cinema 4D from Maxon is a 3D rendering and animation tool suite used by 3D animation houses and producers like Sony Animation and many others.  It's very demanding of system processor resources and is an excellent gauge of pure computational throughput.

 Cinebench R10 Performance Tests
 3D Modeling & Rendering Tests

This is a multi-threaded, multi-processor aware benchmark that renders a single 3D scene and tracks the length of the entire process. The time it took each test system to render the entire scene is represented in the graph below, listed in seconds.

In Cinebench R10's single-threaded benchmark, the Skulltrail platform, powered by a pair of 3.2GHz QX9775 processors performs much like the similarly clocked Core 2 Extreme QX9770.  In the multi-threaded benchmark, however, Skulltrail's eight cores propel the system to the front of the pack, by a wide margin.  In fact, Skulltrail nearly doubles the performance of the QX9770 in the multithreaded test.

POV Ray Performance
Details: www.povray.org

POV-Ray, or the Persistence of Vision Ray-Tracer, is a top-notch open source tool for creating realistically lit 3D graphics artwork. We tested with POV-Ray's standard included benchmarking model on all of our test machines and recorded the scores reported for each.   We shoudl also note that we used the latest 64-bit beta build of the program.  Results are measured in pixels-per-second throughput.

POV-Ray's multithreaded SSE2 benchmark tells essentially the same story as Cinebench R10.  The immense performance of eight cores clocked at 3.2GHz allow the Skulltrail system to significantly outpace every other system.

Kribibench and 3DMark06

For this next batch of tests, we ran Kribibench v1.1, a 3D rendering benchmark produced by Adept Development.  Kribibench is an SSE aware software renderer where a 3D model is rendered and animated by the host CPU and the average frame rate is reported. 

Kribibench v1.1
Details: www.adeptdevelopment.com

We used two of the included models with this benchmark: a "Sponge Explode" model consisting of over 19.2 million polygons and the test suite's "Ultra" model that is comprised of over 16 billion polys.

Kribibench tells an interesting story.  In the sponge explode model test, the Skulltrail system performs much like the QX9770, despite the fact that this is a multi-threaded benchmark.  With the more taxing Ultra model, however, the Skulltrail rig pulls way out in front.  We beleive this is happening because the sponge explode test is completed so quickly, that all eight cores never hit 100% utilization.

 Futuremark 3DMark06 - CPU Test
 Simulated DirectX Gaming Performance

3DMark06's built-in CPU test is a multi-threaded DirectX gaming metric that's useful for comparing relative performance between similarly equipped systems.  This test consists of two different 3D scenes that are processed with a software renderer that is dependent on the host CPU's performance.  Calculations that are normally reserved for your 3D accelerator are instead sent to the CPU for processing and rendering.  The frame-rate generated in each test is used to determine the final score.

3DMark06's built-in CPU performance module had the Skulltrail rig outperforming the next fastest system, the QX9770 by exactly 1500 points, a delta of just over 30%.

LAME MT Encoding

In our custom LAME MT MP3 encoding test, we convert a large WAV file to the MP3 format, which is a popular scenario that many end users work with on a day-to-day basis to provide portability and storage of their digital audio content.  LAME is an open-source mid to high bit-rate and VBR (variable bit rate) MP3 audio encoder that is used widely around the world in a multitude of third party applications.

 LAME MT MP3 Encoding Test

 Converting a Large WAV To MP3

In this test, we created our own 223MB WAV file (a hallucinogenically-induced Grateful Dead jam) and converted it to the MP3 format using the multi-thread capable LAME MT application in single and multi-thread modes. Processing times are recorded below, listed in seconds. Once again, shorter times equate to better performance.

Despite the "MT" in LAME MT's name, this test utilizes only two threads.  As such, the Skulltrail rig performs identically to the similarly clocked Core 2 Extreme QX9770 based system, which is to say it finished the test at the head of the pack.

Gaming: Crysis and F.E.A.R.

For our last set of game tests, we moved on to some in-game benchmarking with Crysis and F.E.A.R. When testing processors with Crysis or F.E.A.R, we drop the resolution to 800x600, and reduce all of the in-game graphical options to their minimum values to isolate CPU and memory performance as much as possible.  However, the in-game effects, which control the level of detail for the games' physics engines and particle systems, are left at their maximum values, since these actually do place some load on the CPU rather than GPU.

Benchmarks with Crysis and F.E.A.R. v1.08
DirectX 9 and 10 Gaming Performance

Crysis and F.E.A.R. tell two very different stories.  In the Crysis CPU benchmark, the Skulltrail rig performs quite well, but it can't keep pace with the QX9650 or QX9770.  The QX9650 and QX9700 based systems were equipped with much faster DDR3 memory, which offers far more memory bandwidth, and as such the systems are able to outpace Skulltrail.

F.E.A.R., however, was completely CPU bound, and the additional resources afforded by Skulltrails dual-processors and eight cores allowed it to finish the test well ahead of the competition.

Power Consumption and Acoustics

We have a couple of final data points we'd like to cover before bringing this article to a close. Our goal was to give you all an idea as to how much power each of the system configurations we tested used while idling and running under load.  And also speak a bit about Skulltrail's acoustic profile.

Power Characteristics
Processors and Platforms

Please keep in mind that we were testing total system power consumption here at the outlet, not just the power being drawn by the processors alone.  In this test, we're showing you a ramp-up of power from idle on the desktop to full CPU load.  We tested with a combination of Cinebench R10 and SANDRA XII running on the CPU.

Despite Intel's recommendation of a 1000W power supply for Skulltrail when using a single high-end graphics card and a 1400W PSU for multi-GPU configurations, our Skulltrail based test system did not consume an astronomical amount of power in our opinion.  If you consider the Skulltrail rig has a second quad-core CPU, dual PCI Express switches, and AMBs on each FB-DIMM, its idle power of 262 watts is somewhat impressive in light of the competition.  Under load, Skulltrail consumed almost 400W, but considering the amount of horsepower under the hood we don't think that is excessive either, especially in light of the pseudo quad-core QuadFX system.

As for Skulltrail's acoustic profile, we're only going to comment on the motherboard's active Southbridge / PCI Express switch cooler because the CPUs can be cooled using any LGA775 heatsink on the market.  Unfortunately, even the quietest CPU coolers won't completely silence a Skulltrail system because the SB cooler's fan is just plain loud.  Perhaps this will change with a future BIOS revision that will throttle the fan's speed (there is an option in the BIOS that didn't seem to do anything), but with the configuration we tested the SB fan was the loudest part of the system.

Our Summary and Conclusion

Performance Summary: It is very easy to summarize Skulltrail’s performance.  Due to the system’s relatively high-clock speeds and eight processor cores, Skulltrail significantly outperforms every other platform in multi-threaded applications that can utilize all of the system’s CPU resources.  In single-threaded situations as well, the 3.2GHz QX9775 processors with their 1600MHz FSB frequency also allow Skulltrail to finish at or near the head of the pack in most tests.  It’s only in memory bandwidth limited situations, where all of the CPU cores aren’t utilized, that Skulltrail doesn’t dominate due to the use of DDR2-800 FB-DIMMs.

Let’s get the obvious information out of the way first – Intel’s dual Core 2 Extreme QX9775-powered Skulltrail platform is the highest performing setup we have ever tested.  With its eight processor cores and high-clock speeds, Skulltrail is simply in a league of its own.   Due to the unique configuration of the D5400XS motherboard, Skulltrail is also a flexible platform.  Users can run one or two processors, use any LGA775 heatsink, and even take advantage of either ATI’s or NVIDIA’s multi-GPU technology.  About the only major drawback of the D5400XS is its use of FB-DIMMs.

Another aspect of Skulltrail that will surely turn off some of you is its price.  Intel hasn’t disclosed solid figures just yet, but they have said that the QX9775 processors will be priced higher than current “Extreme” edition processors and the motherboard will be somewhat more expensive than the company’s current high-end workstation class offerings.  That puts each CPU somewhere north of a grand a piece and the mobo in the $600+ range.  Factor in a couple of gigs of DDR2-800 FB-DIMMs and you’re talking about roughly $3000 for the configuration we tested here.  Cheap?  Heck no.  Extreme Powerful?  You betcha.

We should also note that Intel hasn’t disclosed when exactly Skulltrail hardware will be made available, but it will be in this quarter according to the most recent information.  For now, you’ll just have to drool over the benchmarks and hope that raise you’ve been asking for comes through.

  • Extreme Performance
  • Eight Cores
  • SLI or CrossFire
  • Flexible Configuration Options
  • Workstation Roots
  • Going to be PRICEY
  • Not Yet Available
  • Loud SB Cooling Fan

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