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VIA K8T890 Series Chipsets
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Date: Sep 24, 2004
Section:Motherboards
Author: Marco Chiappetta
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Introduction & Specifications

When AMD's Athlon 64 was initially introduced, all of the major players in the core logic chipset  business immediately jumped on board, and introduced, or released, full-featured chipsets for the new processor.  And although SiS, ALi, VIA and NVIDIA all had similar Athlon 64 chipsets on their respective road maps, it was VIA and NVIDIA who ended up truly dominating the segment.  VIA's K8T800 and NVIDIA nForce 3 150 Pro locked horns back then, and the battle has raged on ever since.  NVIDIA and VIA essentially fought to a draw on the Socket 754 platform, with each chipset garnering its share of fans, but on the Socket 940 platform the K8T800 was declared the "best" choice, namely because of the excellent support VIA got from Asus in the SK8V.  The SK8V was a top notch motherboard powered by the K8T800, that won numerous editor's choice awards from top technology publications the world over.

Both companies followed up their initial Athlon 64 chipsets a short while later, with NVIDIA introducing the nForce 3 250GB and nForce 3 Ultra, and VIA the K8T800 Pro.  This time around both chipsets offered very similar features and performance.  We recently compared four enthusiast class motherboards powered by the K8T800 Pro and nForce 3 Ultra, and found them all to be excellent choices, but gave the overall nod to NVIDIA's nForce 3 due to their overclockability and a dominant performance in the "real-world" Business and Content Creation Winstone benchmarks.

Today, VIA is upping the ante again with the introduction of the K8T890 and K8T890 Pro chipsets.  The K8T890 series of chipsets brings with it support for the high-speed PCI Express bus standard, along with all of the features already incorporated into the K8T800 Pro.

Specifications Of The VIA K8T890 Series Chipset
Ready For AMD's Best
Support for the latest AMD Opteron, Athlon64, and Sempron Processors
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_Inherits excellent pedigree of existing VIA K8 Series chipsets, which command 90% market share on AMD64 platform

VIA Flex Express Architecture
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_PCI Express x16 Graphics
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_PCI Express x1 High Bandwidth Peripheral connections

Asynchronous Bus Architecture
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_AGP/PCI Lock allows easier tweaking of the CPU

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

DriveStation V-RAID
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_Support for RAID 0, 1 and 0+1 arrays

V-MAP architecture
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_Industry's most scalable system architecture
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_Unified driver base

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

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

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

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

 


The K8T890 is VIA's first chipset to support the emerging PCI Express bus standard that will eventually supplant both the AGP and PCI buses, for graphics and peripheral I/O.  The K8T890 will support the full range of AMD's Athlon 64 processors, including the FX, Opteron and Sempron, in both Socket 754 and Socket 939 flavors. Along with support for a total of 22 PCI Express lanes, the K8T890 Northbridge, when coupled with the VT8251 Southbridge, offers a full 16-bit / 1GHz (2GHz DDR) HyperTransport link between the CPU and Northbridge, which VIA calls "Hyper8".  The K8T890 / VT8251 combo also has support for VIA's Vinyl Audio, which can be configured for 6 or 8 channel operation, VIA's DriveStation with PATA and SATA support including V-RAID, 8 USB 2.0 ports, and the requisite floppy, serial, and parallel connections.  Noticeably absent is an integrated Gigabit Ethernet controller into the Southbridge or SATA2 support, but a Gigabit Ethernet controller can be connected through a PCI Express X1 lane and have ample bandwidth available for full speed operation.  And SATA2 support will likely be coming with an updated Southbridge.

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VIA and PCI Express

The move to PCI Express on the desktop begun with Intel's introduction of their 900 series chipsets back in June. The need for a high-speed serial point to point connections like PCI Express, stems from the fact that the aging PCI bus doesn't offer the performance necessary to sustain bandwidth hungry peripherals like HDTV tuner cards and high-end SCSI or SATA controllers.  But until now, PCI Express wasn't available on AMD based systems.

VIA and PCI Express
It's All About Bandwidth!

 

So, why shift towards PCI Express when it hasn't shown any real-world performance benefits just yet?  It's due to the fact that at 133MB/s the PCI bus has become one of the slowest links in a personal computer.  Virtually every other connection in a system has been upgraded over the years, offering far more bandwidth than PCI.  Not to mention, PCI is a shared bus architecture, so all peripherals on PCI share the available bandwidth.   A 1GHz HyperTransport link, for example, offers up to 8GB/s of bandwidth, and the aging AGP spec has been upgraded to the point where it now offers up to 2.1GB/s of bandwidth.  Even, VIA's own Ultra V-Link technology, which connects their Northbridge and Southbridge chips on a motherboard, offers almost 10x the bandwidth of PCI.  The PCI bus, however, which is used for a myriad of expansion cards offers a maximum of a mere 133MB/s, and that 133MB/s is shared amongst all of the devices on the bus.  Connect a fast SATA hard drive to a PCI RAID controller, along with a PCI connected Gigabit Ethernet controller, and an PCI HDTV tuner card, and saturating the bus is easy.  Which is why dedicated PCI Express links have become increasingly more necessary.

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VIA's Flex Express Architecture

 

VIA's PCI Express implementation, which they're calling their 'Flex Express' architecture, is fairly flexible in that it has the ability to distribute PCI Express bandwidth across the North and Southbridge chips.  The K8T890 Northbridge is directly linked to 20 PCI Express lanes, and the VT8251 Southbridge has two of its own PCI Express links, for a total of 22 PCI Express lanes.

VIA's Flex Express Architecture
Connections to the North and South Bridge...

 


When both the K8T890 Northbridge and the VT8251 Southbridge are used in conjunction, a total of 7 PCI Express devices are supported, with a total of 5.5GB/s of available bandwidth (11GB/s concurrently).  The total of seven devices is derived from the fact that 16 of the PCI Express lanes that are part of the Northbridge are used for the PEG video card slot, leaving 4 left to be used in up to four PCI Express X1 slots. The VT8251 Southbridge houses another 2 PCI Express lanes, adding two more PCI Express X1 slots, for a total of 7 devices (Graphics + 6 PCI Express X1 peripherals).  It's not likely that we'll see many K8T890 powered motherboard setup in this configuration for quite some time, however, as PCI Express X1 cards have yet to emerge in any quantity.  Standard PCI slots will be common for the foreseeable future.

This type of distributed setup is beneficial because high-bandwidth devices, like a Gigabit Ethernet controller for example, can be connected directly to the Northbridge, while less demanding peripherals can be connected to the Southbridge.  We should also note that the K8T890 Northbridge is compatible with all past VIA Southbridges, and should be compatible with future Southbridge chips as well.  So the total number of PCI Express lanes, and the entire feature-set for that matter, could change in future versions of the K8 series chipsets.

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VIA Dual GFX Express

As most of you are probably aware, NVIDIA and Alienware have the gaming community buzzing at the prospect of running dual PCI Express graphics cards in a single system for increased performance.  Although VIA hasn't made any announcements claiming "SLI-type" support in their S3 DeltaChrome 3D GPUs, they're going to offer support for dual PCI Express video cards with the K8T890 Pro version of the chipset...

VIA Dual GFX Express
Graphics Taken to Another Level

 

As you can see in the image above, VIA's "Dual GFX Express" technology offers full support for dual PCI Express graphics card implementations.  Although astute observers may notice that each of the graphics cards connected to the Northbridge in the block diagram above, don't have the number of PCI Express lanes per connection specified.  We've been told that a DualGFX motherboard will feature 2 Graphics slots, and one slot will have 16-lanes and the secondary slot will have 4-lanes.  4-lanes provides approximately 2GB/s of overall bandwidth, and in comparison AGP 8x at its max provided 2.2GB/s.

Also note that the additional 4 PCI Express X1 lanes shown in the K8T890 block diagram aren't listed in this images depecting the K8T890 Pro.  In this case,we were told that all 20-lanes are being used by the graphics implementation. On this platform PCI Express x1 connectivity will be provided through VIA's upcoming VT8251 South Bridge.

Another thing to note is the dual PCI Express graphics slots, aren't just for gamers.  Users can simply enjoy the benefits of having dual graphics cards in a system.  Aside from the performance increases having an NVIDIA SLI configuration will offer, having dual graphcis cards will give users the ability to run dual independant applications accelerated on each card.  You could have Maya running, fully accelerated, on one monitor, with 3D Studio Max running on the other.  Plus, there's the benefit of having dual video cards, powering up to four displays.  And this support is already built into Windows XP.

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Feature Comparison & Conclusion

As we mentioned earlier, the VIA K8T890 will be available in two flavors, the standard VIA K8T890 and the K8T890 Pro. Here's a breakdown of their distinct features and target audiences.  Both the K8T890 and K8T890 Pro support the same Southbridge, so they share many of the same features and capabilities.

VIA K8T890
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_PCI Express x16 Graphics
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_4 PCI Express x1 Peripherals

·_Up to 4 PCI Express x1 high bandwidth peripheral connections make it a suitable platform for entry level server market
·_World's first chipset to bring support for latest PCI Express x16 Graphics cards to AMD64 platform

·_Advanced users and PC Enthusiasts
·_OEMs wishing to offer first generation PCI Express solutions for the AMD Athlon 64 platform
VIA K8T890 Pro
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_DualGFX Express Graphics
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_2 PCI Express x1 Peripherals

·_VIA Dual GFX Express delivers exceptional single application performance and powerful multitasking support
·_Supports 2 applications on different screens and up to 4 displays
·_Support for Dual Opteron processors

·_Ideal platform for workstations in engineering, scientific and medical environments
·_Creative professionals and power users

The main differences between the K8T890 and K8T890 Pro lie in the Pro version's Dual GFX capabilities, the use PCI Express lans, and the Pro's support for dual Opteron processors.  While the K8T890 Pro will have many gamers salivating at the ides of running dual NVIDIA GeForce 6x00's in an SLI configuration, professionals looking for a high-end dual-processor workstation should also take notice. 

The VIA K8T890 and K8T890 Pro chipsets are a necessary evolutionary upgrade to the AMD64 platform.  The lack of PCI Express support for AMD processors makes many potential customers pause.  They simply don't want to upgrade because they fear their graphics cards and motherboards could soon be obsolete.  Now, with the K8T890 and K8T890 Pro these users can upgrade without this fear.  The K8T890, in it's various forms, is a very full-featured solution that should satisfy both gamers and professionals alike.  We hope to have retail-ready motherboards from a few manufacturers in the weeks and months ahead, to assess the real-world performance of the K8T890 in a variety of scenarios.  Abit, for example, has already announced their AX8 - you can check it out right here.  We also fully expect NVIDIA to make some noise of their own.  Their next generation nForce chipset should be a direct competitor to the K8T890 series of chipsets, and may even offer some features that haven't previously been available on the PC.  We'll let you know more as the information trickles in...or when the NDAs expire, which ever happens first!

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