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VIA's K8T900 Chipset
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Date: Nov 22, 2005
Section:Motherboards
Author: Jeff Bouton
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Introduction and Product Specifications

With the adoption of PCI Express as a next-gen I/O technology, all of the major chipset manufacturers worked hard to bring compatible chipsets to market.  Naturally, Intel was first on the scene with the 900 series chipsets. But on the AMD side, VIA was first to market with its K8T890 Chipset.   Building on the successes of the K8T800, which competed on the same level as nVidia's nForce 3 250 and nForce 3 Ultra, VIA aimed to take things to the next level with new features and improved overall performance.  By coupling the K8T890 Northbridge with the promising VT8251 Southbridge, VIA's first PCI Express ready chipset aimed to deliver a number of new features, the most notable being the first dual-PCI Express graphics implementation with DualGFX Express. 

Since the release of the K8T890 back in September of 2004, however, VIA has become virtually silent about the K8T890.  When we scan the major players' product lines, we see a few K8T890 models being offered by such companies as Abit, ASUS, EPoX and MSI, but none were equipped with the VT8251 Southbridge, nor were there any Pro versions with DualGFX Express as planned.  As it turned out, VIA had some major difficulties perfecting the audio and RAID 5 functionality of the VT8251.  In fact, VIA had to rework the design of the VT8251 five times before ironing out all the kinks. Now, over a year later, VIA is ready to bring the VT8251 to market in conjunction with a re-worked Northbridge.

In the time it took to retool the VT8251, VIA made some design changes to the K8T890 Northbridge as well, bringing to light the new K8T900, which we will be discussing today.  The new K8T900 adds further enhancements to the PCI Express implementation, aiming to deliver increased performance over the competition while offering dual-PEG slots as well.

Specifications: VIA's K8T900/VT8251 Chipset
Picking Up Where the K8T890 Left Off
Support for the latest AMD Opteron, Athlon64, and Sempron Processors

VIA RapidFire Technology
dual PCI Express x16 slots
Reduced Latency and Improved Signal Quality delivers increased performance for high-bandwidth graphics solutions
Lower Power Consumption

VIA Flex Express Architecture
·PCI Express x16 Graphics
·PCI Express x1 High Bandwidth Peripheral connections

Asynchronous Bus Architecture
·allows easier tweaking of the CPU

Hyper8 Technology
·Full 1GHz/16-bit implementation of HyperTransport bus link between CPU and chipset

DriveStation V-RAID
·Support for RAID 0, 1 and 0+1 arrays

V-MAP architecture
·Industry's most scalable system architecture
·Unified driver base

VIA Flex Express Architecture
·Industry's most flexible PCI Express chipset implementation
·Multiple device configurations
·Motherboard Manufacturers and SIs can meet the needs of various market segments with one scalable solution

Expanding PCI Express to Mature Platforms
·Bringing PCI Express connectivity to mature platforms Distributed PCI Express Bandwidth
·South Bridge bandwidth increasingly taken up by IDE/SATA drives, peripherals and multimedia devices
·Peripheral bandwidth distributed across chipset's North and South Bridge to minimize bottlenecks

Flexible PCI Express Configurations
·The shift to PCI Express is creating some compatibility headaches for the industry
·New standards, bus architectures, interfaces and connectors to deal with

VIA's unique Flex Express Architecture designed to make the transition easier
·With up to 22 PCI Express lanes, the industry's most flexible chipset implementation allows multiple configurations
·Flexible, pin-compatible design approach across VIA chipsets minimizes motherboard design process and time-to-market
·Motherboard partners can cover multiple segments with single core board design

 


 

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The K8T900 & VT8251 Chipset Overview
VIA's K8T900 and VT8251 Chipsets - Up Close
Breaking It Down

When we scan the chipset schematic of the K8T900, the picture is very similar to that of the K8T890 when it was first announced.  The K8T900 supports all AMD processors, including both single and dual core models from socket 754, 939 and 940.  The K8T900 brings 20 PCI Express lanes to the table, represented as four PCI Express x1 slots and two PCI Express x16 graphics slots, with x8 electrical connections, linked directly to the Northbridge.  We should note that VIA also spent some time tweaking the PCI Express implementation, claiming performance increases of 3-5% over the competition.  We were told the same engineer that re-worked the KT266a's excellent memory controller tweaked the K8T900's PCI Express implementation.

Communication between the Northbridge and CPU is handled by VIA's Hyper8; a 16-bit HyperTransport Bus that runs at 1GHz (2GHz DDR) for 8GB/s of total bandwidth with socket 939 CPUs, while socket 754 and 940-pin configurations run at 800MHz (1600MHz DDR) for 6.4GB/s bandwidth.  When combined with the VT8251 Southbridge, the K8T900 delivers a total of 22 PCI Express lanes, 20 with the Northbridge (x16 PEG and four PCI Express x1 connections) supporting 5 devices at 5GB/s of total bandwidth.  The Southbridge offers two additional lanes totaling .5GB/s of bandwidth across two PCI Express x1 devices.

The VT8251 Southbridge brings eight USB 2.0 ports, seven PCI slots, 2-lane PCI Express and integrated 10/100 Ethernet.  The Southbridge utilizes VIA's DriveStation to bring a host of storage features and flexibility.  The DriveStation SATA controller offers 4 SATA II ports along with implementing Native Command Queuing for supporting devices.  The controller also adds Hot-Swap capability along with staggered spin-up functionality to reduce power draw on initial startup.  The parallel PATA controller offers two IDE connections supporting 4 ATA133 devices while VIA's V-RAID Controller delivers RAID 0, 1, 0+1, 5 and JBOD.

VIA offers three options in regards to integrated audio with VIA's Multichannel Audio Suite.  The first is VIA's 20-bit/48kHz Vinyl AC'97 which is VIA's most basic 7.1 channel audio offering.  The next level is VIA Vinyl HD Audio that brings 32-Bit 7.1 channel audio to the mix at 192kHz.  Topping out the trio is VIA Vinyl Gold 7.1 surround driven by the VIA Envy24PT chip.  Coupled with VIA Six-TRAC and an additional DAC, VIA Vinyl Gold offers the broadest array of features while delivering 24-bit /192kHz quality.

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Dual PCI Express with RapidFire
Dual PEG and Multi-GPU Support
MultiChrome

Back when the K8T890 was introduced, VIA introduced the DualGFX Express technology which would allow two PCI Express Graphics cards on a single system.  The goal was to offer a single PCI Express x16 slot along side a secondary PCI Express x4 slot for enhanced multi-monitor support.  This implementation would allow applications to be accelerated on both cards while supporting up to four monitors.

With the K8T900, VIA dropped the idea of a dedicated PCI Express x16 and secondary x4 PCI Express graphics slot in favor of a more balanced approach with RapidFire.  The K8T900 chipset provides two PCI Express graphics connections with 8 PCI Express lanes per connection, or 16 PCI Express lanes when one card is used, similar to the nForce 4 SLI configuration.  Additionally, with VIA's tweaking of the PCI Express implementation, VIA claims graphics performance increases of 3 to 5% when compared to the competition, namely the nForce 4, when running high-bandwidth graphics solutions.

We mentioned earlier that VIA's dual-PEG implementation was similar to the nForce 4 SLI, so much so that VIA utilizes a very similar transposer card to alter the lane configuration on their reference board.  This doesn't mean the board is SLI or Crossfire capable, however.  The hardware implementation is in place and VIA sees no reason for SLI or Crossfire not to work.  In fact, VIA's own in house testing has shown it should work with supporting drivers.  However, the two technologies have not been validated to function on the K8T900 by ATI or NVIDIA thus far, leaving the ball in NVIDIA and ATI's court. 

There is one multi-GPU implementation that the K8T900 has been validated to work with, that being S3 Graphics MultiChrome technology.  MultiChrome is an open-platform technology that allows two of S3's Chrome S27 graphics cards to function together on any motherboard equipped with two PCI Express graphics slots, regardless of chipset.  S3's approach is to have two Chrome S27 cards run together by using a multi-GPU driver set rather than relying on hardware connections between the two graphics cards.

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MultiChrome Overview
S3's MultiChrome multi-GPU Technology
A Simpler Approach

S3's approach to multi-GPU support is to handle the process through drivers rather than with proprietary hardware or cables, in the same way NVIDIA does it with low-end GeForce 6600's and ATI does with the X1300 and X1600.  With S3's new S27 Chrome graphics cards, two cards can be installed and a special driver is all that is needed to combine GPU processing.  This approach not only avoids bridge clips or cables, it also enables the technology to be open platform, free to function on multiple chipsets supporting two PEG slots.  The only catch at this point is that MultiChrome only works with two S27 Chrome graphics cards, although it's a safe bet more models will support MultiChrome in the future.

Essentially, S3 crafted MultiChrome drivers that split the video processing equally between two S27 Chrome graphics cards using two methods.  The first is Split Frame Rendering which does as its name implies, splits a single frame so each card processes half of a frame.  The next method is Alternative Frame Rendering which sends one frame to one S27 Chrome card while the next frame is delivered to the other one.  Below is a grid showing what performance increases we should expect with a MultiChrome Configuration. 

The performance increases are represented in percentages rather than FPS and show a wide range of variation.  Compared to a SLI or Crossfire set up, MultiChrome appears to work better with some games than others.  Keep in mind, though, that the Chrome 27 is an affordable card not intended to compete with high-end graphics cards as we are used to seeing. 

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VIA's VT5925A K8T900 Reference Motherboard
VIA's VT5925A K8T900 Reference Motherboard
A Quick Look

The motherboard we received for this review was a reference design that is not necessarily indicative of what full retail models will represent.  Component layout was not ideal and the board lacks any "sex appeal".  With that said, we're not going to spend a lot of time on the physical features of the board or the BIOS.  Nonetheless, we thought we'd drop in a few snapshots to show what hardware we had to work with along with some BIOS pics and overclocking.

  

 

The reference board came with two PEG slots, two along side two PCI slots.  Note that power connections are in a less than perfect position when it comes to cables draping over the CPU cooler.  VIA did add passive cooling to the Northbridge, which was warm, but not piping hot, under load.  Note the four SATA ports lined up next to a vertically mounted BIOS battery.  The board also came with only one IDE connection and was equipped with onboard power and reset switches which we found handy for testing.

The BIOS of the VT5925A was labeled "Not for Production", as we commonly see with engineering samples, but we fired off a few pics to show what was under the hood.  Overall, the menus were standard fare with a familiar look.  Performance options were all typical for the most part and we suspect retail boards will follow a similar layout.

  

 

 

As you can see, the reference hardware is not equipped with the necessary BIOS for serious overclocking, with a peak register setting of 232MHz.  Nonetheless, we gave overclocking a shot anyway.  Knowing the peak setting was well within the scope of what our processor can handle, we jumped right to 232MHz from the first try with no voltage adjustments whatsoever.  This pushed our Athlon 3700+ from 2.2GHz up to 2.55GHz without a hitch and the system booted straight into Windows unscathed.  We'll have to wait for the full retail boards to reach the market, however, before we see what the K8T900 can really do in the overclocking arena, but this was a good start.

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HH Test Bed and SANDRA

How we configured our test systems: When configuring the test systems for this review, we first entered their system BIOSes and set each board to its "Optimized" or "High-Performance Defaults."  The hard drives were then formatted, and Windows XP Professional (SP2) was installed. When the Windows installation was complete, we installed the rest of the necessary drivers and removed Windows Messenger from the system.  Auto-Updating and System Restore were disabled, and we set up a 768MB permanent page file on the same partition as the Windows installation. Lastly, we set Windows XP's Visual Effects to "best performance," installed all of our benchmarking software, defragged the hard drives, and ran all of the tests.

Test System Specifications
AMD nForced Here
SYSTEM 1:
AMD Athlon 64 3700+
(2.2GHz)

VIA VT5925A K8T900 Reference
(K8T900/VT8251)

2x512MB PQI3200-1024DBU
CL 2-2-2-5

GeForce 6800 GT
On-board Ethernet
On-board Audio

WD 80GB Hard Drive
7200 RPM IDE

Windows XP Pro SP2
VIA HyperionPro 5.04a
NVIDIA Forceware v81.58
DirectX 9.0c
SYSTEM 2:
AMD Athlon 64 3700+
(2.2GHz)

ECS KN1 SLI Extreme
(NVIDIA nForce 4 SLI)

2x512MB PQI3200-1024DBU
CL 2-2-2-5

GeForce 6800 GT
On-board Ethernet
On-board Audio

WD 80GB Hard Drive
7200 RPM IDE

Windows XP Pro SP2
nForce 4 Drivers v6.70
NVIDIA Forceware v81.58
DirectX 9.0c
Software:
SiSoft Sandra 2005
FutureMark PCMark05
Content Creation Winstone 2004
PC World's World Bench 5.0
-Photoshop 7 Module
-Office XP SP2 Module
-Windows Media Encoder 9 Module
Lame MP3
Adept Development's KribiBench v1.1
Cinebench 2003
Unreal Tournament 2004
Doom 3


Preliminary Benchmarks with SiSoft SANDRA 2005
Synthetic Testing

We began our testing with SiSoftware's SANDRA, the System ANalyzer, Diagnostic and Reporting Assistant. SANDRA consists of a set of information and diagnostic utilities that can provide a host of useful information about your hardware and operating system. We ran four of the built-in subsystem tests that partially comprise the SANDRA 2005 suite (CPU, Multimedia, Cache, and Memory).  All of the scores reported below were taken with the processor and memory running at their respective default clock speeds of 2.2GHz and 200MHz (DDR400).


CPU Arithmetic Benchmark

Multimedia Benchmark

CPU Cache Benchmark

Memory Benchmark

Generally, we like to use SiSoft SANDRA 2005 to give a quick insight into a product's performance potential compared to SANDRA's extensive database of comparison hardware.  With the K8T900 reference board, all results were within the scope of what we would expect from this particular set up.  CPU and MultiMedia performance was on target for our Athlon 64 3700+ while memory performance was equally competitive.  In pages ahead, we'll attempt to narrow down the performance scope with a broad range of testing applications in an effort to paint a more definitive performance picture.

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Futuremark PCMark05
Futuremark PCMark05
More Synthetic CPU and Memory Benchmarks

Rounding out our synthetic benchmark test, we ran the CPU and Memory performance modules built into Futuremark's PCMark05.  From this point forward, we'll be comparing the performance of the K8T900 reference motherboard to the ECS KN1 SLI motherboard based on the nForce4 SLI chipset.


With PCMark05's CPU module, the ECS motherboard yielded slightly higher results, topping the VIA K8T900 by 21 PCMarks.  With memory performance, the scales continued to favor the nForce SLI system with the VIA K8T900 reference test bed lagging the ECS model by 81 PCMarks.

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Content Creation 2004 and WB 5.0: Photoshop 7 & Office XP

To get this next batch of results, we used Veritest's Content Creation Winstone 2004 suite.  Before running these benchmarks, we patched the program to its latest version (v1.01), shut-down any unnecessary background processes, and defragged the hard drive.

Content Creation Winstone 2004
Real-World Application Performance

The Veritest Content Creation Winstone 2004 test utilizes the following applications in its benchmark routine. For more information about this test, see this page:

  • Adobe Photoshop 7.0.1
  • Adobe Premiere 6.50
  • Macromedia Director MX 9.0
  • Macromedia Dreamweaver MX 6.1
  • Microsoft Windows Media Encoder 9 Version 9.00.00.2980
  • NewTek's LightWave 3D 7.5b
  • Steinberg WaveLab 4.0f

With the multimedia intensive Content Creation Winstone 2004, both test beds returned nearly identical results, with no clear leader.

PC World's World Bench 5.0: Photoshop 7 & Office XP Modules
More Real-World Application Performance

PC World Magazine's WorldBench 5.0 is a new breed of Business and Professional application benchmark, poised to replace the aging and no-longer supported Winstone tests. WorldBench 5.0 consists of a number of performance modules that each utilize one, or a group of, popular applications to gauge performance.  Below we have the results from WB 5's Photoshop 7 and Office XP modules, recorded in seconds.  Lower times indicate better performance.

WorldBench 5's Photoshop module was the first test where we saw the K8T900 take a slight lead over the nForce 4 SLI equipped ECS KN1 SLI.  The VIA reference motherboard lead by 5 seconds, equating to approximately 1.5%.

With the Microsoft Office XP SP2 Module, we recorded a four second advantage in favor of the K8T900, equaling less than 1% overall.

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Windows Media Encoder 9 and LAME MP3

We continued our testing with WorldBench 5's video encoding benchmark based on Windows Media Encoder 9.  Lower times indicate better performance.

World Bench 5.0 - Windows Media Encoder 9
More Digital Video Encoding

Once again, we saw a slight edge in favor of VIA's K8T900 reference board, beating the nForce 4 SLI comparison board by 4 seconds, a 1 % difference. 

LAME MP3 Encoding Test
Converting a Large WAV To MP3

In our custom Lame MP3 encoding test, we convert a large digital audio file to the MP3 format.  In this test, we chose a large 223MB WAV file (a never-ending Grateful Dead jam) and converted it to the MP3 format. Processing times are recorded below. Shorter times equate to better performance.

With LAME MP3 Encoding, both test platforms were essentially tied, with the K8T900 edging out the ECS KN1 SLI Extreme system by 1 second. 

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Kribibench v1.1 and Cinebench 2003

Next up, we ran the Kribibench rendering benchmark produced by the folks at Adept Development.  Kribibench is an SSE aware software renderer.  A 3D model is rendered and animated by the host CPU, and the average frame rate is reported.  We used two of the included models with this benchmark: an "Exploded Sponge" model consisting of over 19.2 million polygons and then its enormous "Ultra" model that is comprised of over 16 billion polygons.

Kribibench v1.1
Details: www.adeptdevelopment.com

In the Sponge Explode test, the test bed built on the K8T900 reference board was the top performer by 1.3% at 2.24 FPS while the Ultra Model test had the two test beds tied at .62.

Cinebench 2003 Performance Tests
3D Modeling & Rendering Tests

Our next test was with Cinebench 2003.  This test is a multithreaded application, however, since the Athlon 64 3700+ is a single core CPU, only single-thread testing was completed.

With Cinebench 2003, the VIA K8T900 test system reached a slightly higher result over the nForce 4 SLI comparison system.  Peaking at 85.3, the K8T900 lead the competitor board by just over 1%.

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Unreal Tournament 2004 and Doom 3

Next we delved into the gaming side of things a bit and performed some low-resolution benchmarking with Epic's Unreal Tournament 2004.  We specifically used a "Low-Quality" game setting with UT2004 which allows us to isolate CPU and memory performance with little burden on the graphics subsystem.

Unreal Tournament 2004
DirectX 8 Gaming Performance

In Unreal Tournament 2004's low resolution testing, the K8T900 competed closely with the comparison test bed, topping it by a fraction of a frame per second.

Benchmarks with Doom 3
OpenGL Gaming Performance

For our next game test, we benchmarked all of the test systems using a custom multi-player Doom 3 timedemo. We cranked the resolution down to 640 x 480 and configured the game to run at its "Low-Quality" graphics setting. Although Doom 3 typically taxes today's high-end GPUs, when it's configured at these minimal settings it's more CPU / Memory-bound than anything else...

Doom 3's low resolution testing showed the VIA K8T900 reference motherboard lagging the nForce 4 SLI comparison system by 1 FPS, which leaves us safely declaring a tie at these frame rates.

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Peformance Summary and Conclusion

Performance Summary:  Synthetic testing favored the nForce 4 SLI based test bed, topping the VIA K8T900 set up in both memory and CPU testing with PCMark05.  However, when we started more specific tests, more often than not, the K8T900 held the upper hand over the nForce 4 by the slightest of margins.  These leads were very close and in most cases should be interpreted as a tie.  This shows the K8T900 brings comparable performance to that of the market leading nForce 4.

VIA's latest chipset for the AMD platform brings new competition to the foray with competitive performance and features.  The K8T900, matched with the VT8251 Southbridge, has a lot to offer OEM's with the flexibility to easily configure various flavors of the K8T900 to existing designs.  Since the K8T900 can replace the K8T890 pin-for-pin, OEM's will have an easier time adopting the newer chipset to existing board designs, which will have a positive impact on overall costs.

The only chink in the K8T900's armour is support for SLI and Crossfire which gives NVIDIA and ATI a bit of leverage.  The hardware is in place, but it's up to them to make the necessary driver changes to support the K8T900.  Certainly, the K8T900 does support S3's MultiChrome dual-GPU technology, however, that is a smaller market that focuses on the budget conscious and workstation consumer.  Nonetheless, if MultiChrome fits your needs or SLI/Crossfire is not a concern, the K8T900 offers solid performance backed by a quality feature set.

You can expect K8T900 based motherboards to hit the market fairly soon.  Once stock of existing K8T890 motherboards start to dwindle, the K8T900 will rise to replace it as the chipsets are pin-compatible and partners can use the new Northbridge with their existing motherboard designs.  New designs with dual-PEG slots should arrive a little later. We were told RapidFire capable boards will arrive around February of 2006.

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