VIA PT880 Chipset Preview
A Performance Preview of VIA's Dual-Channel P4 Chipset

By: Chris Angelini
December 8, 2003

         

For the first time since NVIDIA unveiled its nForce2 chipset more than a year ago, VIA is in a very promising position.  To begin, AMD's Athlon 64 is upon us, bringing with it an integrated memory controller that really equalizes the advantage NVIDIA once enjoyed.  In fact, the nForce3 and K8T800 chipsets generally fall within a percentage or two of each other in performance benchmarks.  VIA's leg-up comes in the form of an encompassing feature set.  Its VT8237 South Bridge includes native Serial ATA support and eight USB ports, compared to NVIDIA's single-chip nForce3 that lacks Serial ATA, is limited to six USB ports, and doesn't include the SoundStorm audio processor that garnered so much acclaim.

VIA's top-end K7 platform, KT600, isn't nearly as compelling.  Quite simply, it lags behind nForce2 in both the performance and feature departments.  Nevertheless, it makes up a lot of ground lost by its predecessor, KT400, which is particularly impressive because KT600 still relies on a single-channel memory architecture.

The latest development from VIA doesn't revolve around Athlon 64 or Athlon XP, though.  This go 'round, the Taiwanese firm is dedicating some attention to its Pentium 4 lineup.  VIA knows full well that its principal competition is the same company that manufactures the Pentium 4.  Yet, it's still gunning for the same level of performance as Intel's 875P 'Canterwood' chipset.  PT880 is the product of a memory architecture re-design, a feature-laden South Bridge, and a faster link between the two chipset components.  It isn't widely available just yet, but when PT880 boards finally do arrive, representatives from VIA expect that they will cost between $70 and $90.  How's that for performance on a budget?

VIA's PT880 Chipset
PT800 on Steroids

As we perused the show floor of Computex in Taipei, Taiwan this year, we noticed several motherboard vendors with PT800-based designs.  Prior to the show, we even managed to secure Biostar's own PT800 board for testing.  And while the PT800 features support for Intel's 800MHz front side bus, it only works with a single channel of DDR memory, instantly crippling potential performance.  Incidentally, you can find PT800 boards online for less the $50 dollars.  We're more interested in enabling performance, though, so when VIA called eager to demonstrate its PT880 reference board, we gladly obliged. 

Of course, the primary difference between PT800 and PT880 is a second 64-bit memory channel, yielding 6.4GB per second of theoretical bandwidth.  Among the improvements reportedly made to VIA's DualStream64 memory controller, an enhanced data prefetch protocol, an improved memory branch predictor, and tighter clock timings are among the most notable.  The controller accommodates everything from DDR266 to DDR400 184-pin modules, including Quad-Band Memory, projected to emerge at some point in 2004.  In turn, the PT880 North Bridge interfaces with a Pentium 4 processor on a 400, 533, or 800MHz front side bus.  Like Intel's 875P and 865 chipsets, PT880 fully supports Hyper-Threading Technology.  It also sports the obligatory AGP 8x compliance.

Another important distinction between PT880 and the value-oriented PT800 is the path connecting the North and South Bridges.  Previously, all of VIA's chipsets featured a 533MB per second interconnect dubbed V-Link.  The latest version, Ultra V-Link, runs at up to 1GB per second, delivering more than enough throughput to the myriad of devices that interface with VIA's VT8237 South Bridge. 

The VT8237 South Bridge is a fairly recent development in itself.  VIA divides the South Bridge's feature set into three categories: VIA Vinyl Audio, VIA DriveStation, and VIA Connectivity.  Vinyl Audio refers to the chipset's integrated AC'97 codec, in addition to an optional onboard 7.1-channel Envy24PT processor.  The DriveStation is actually a two-channel parallel ATA controller, with support for up to four devices and an integrated two-channel Serial ATA controller equipped with RAID 0, 1, and 0+1 support.  When motherboards based on the chipset ship, they'll include software to enable RAID configurations "on the fly," or after an operating system has already been installed on a single drive. VIA Connectivity includes all of the other South Bridge technologies, like USB 2.0 (eight ports), PCI slots, 10/100 Ethernet, and I/O devices. 

VIA's PT880 Reference Motherboard