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VIA's PCI Express plans for late 2004

by Ryszard Sommefeldt on 24 September 2004, 00:00

Tags: Intel (NASDAQ:INTC), AMD (NYSE:AMD), VIA Technologies (TPE:2388)

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VIA's PCI Express plans for late 2004

With Intel introducing their platform transition for Pentium 4 and Xeon processors recently, enthusiasts and early-adopters turned to the AMD core logic providers and wondered when PCI Express, the most interesting part of Intel's new platform, would make its appearance with AMD processors as a means for graphics and peripheral connection.

NVIDIA recently hinted at nForce4, a product we expect to formally launch within the next couple of weeks or so, a product that will most definitely carry the PCI Express tools needed for full support on the AMD platform, including support for NVIDIA's multi-GPU SLI graphics solution. But first to the initial PCI Express and AMD punch - with a product they strongly hinted to us would launch soon when we met them at ECTS - are VIA, with their PCI Express chipset plans for AMD.

VIA's K8T890 Athlon 64, Athlon FX, Opteron and Sempron core logic

The K8T890 northbridge, at it's most basic, is their existing K8T800 Pro core logic with the AGP graphics interface dropped for a full PEG16X PCI Express interconnect, along with four other PCI Express 1X lanes. Swap out AGP for 20 lanes of PCI Express, et voila. It retains support for all Socket 754, 939 and 940 processors, but it doesn't look like we'll see many 754 implementations initially, unless I'm reading things wrong. Also note that it doesn't support dual Opteron in its initial form, rather you'll have to wait for K8T890 Pro for that. More on that particular northbridge soon.

Using the processor's support for memory technologies, you'll see DDR400 support across the board (bar early Opteron core revisions), in dual-channel mode in supporting CPUs, and all of the good performance you've already come to expect from VIA's K8 core logic in the northbridge. While the CPU is responsible for most of that performance, the core logic has some say in how it's implemented, especially if you like to adjust CPU parameters. In that respect, with full support for asynchronous HTT/PCI Express operation, where the HTT clock can be adjusted separately from any other running bus in a K8T890 system, the K8T890 northbridge appeases the habitual tweaker and enthusiast.

The northbridge shares the same Ultra V-Link connection to VIA's excellent southbridge ASICs (K8T890 is likely to be paired with VT8237 initially, with VT8251 popping up soon, more on that shortly) as K8T800 and K8T800 Pro, so that's a ~1GB/sec lane of communication between both parts of a full chipset.

It's PCI Express instead of AGP to be brief. While the other four 1X lanes implemented by the K8T890 are notable in their inclusion, it's southbridge-based PCI Express lanes that are most likely to see peripheral interconnect action in shipping hardware. 1X lanes in PCI Express are expected to phase out older PCI Conventional (the existing 32-bit, 33MHz slots you're used to seeing on mainboards, that you're most likely to plug something like a soundcard or FireWire host adaptor into) in the next year to eighteen months, but until then they'll still be pervasive, before slowly being phased out, as peripherals that use PCI Express are introduced to market.

VIA's K8T890 Pro

The Pro is everything the normal variant is, but with one extra twist. It support dual PEG16X graphics cards on a pair of PEG16X electrical interfaces, but those interfaces share a full PEG16X lane implementation, giving each graphics card eight dedicated lanes. Four up and four down means 2GB/sec in each direction, concurrently, per graphics board. Think AGP8X in both directions, per card, in the same system. With NVIDIA's nForce4 touting the very same feature, almost in exactly the same way (possibly with some switching fabric between the boards and the PEG16X host on the northbridge), it'll be interesting to see how that all pans out. VIA claim SLI support with any pair of PEG16X graphics cards, regardless of SLI being built into the GPU or not, as is the case with a few models in NVIDIA's 6800 and 6600 series' of new GPUs.

While we wait for VIA to figure out the specifics, it's still pencilled in for a 2004 launch, so keep your eyes peeled for that.

VIA's VT8251 Southbridge

VIA, in my opinion, make the best overall southbridge products on the market. They're maybe not the best in all specific areas (SiS make a fantastic disk controller for example, outperforming VIA's southbridge-based efforts), but they're certainly the choice du jour for an overall southbridge package. VT8237 hit the SATA product market running, bundling lots of on-board USB2.0, an Ethernet interface and competent audio signal generation to boot.

VT8251 adds two lanes of PCI Express, retains the older audio support but also adds a full implementation of Intel's HD Audio (Azalia), with full support for all the HD Audio CODECs you've seen recently on shipping Intel mainboards, and it also beefs up its support for SATA, with two more native ports without needing a physical link for any (VT8237 supports two, with two more via an external PHY), with those four native ports also supporting AHCI (also dubbed SATA2, which includes performance enhancements such as command queueing) and VIA's DriveStation RAID modes.

The best southbridge just got better. It's a technical tour-de-force and the defining part of any Athlon 64 or Sempron solution from VIA, given that the basics in northbridge production and features are mostly done on the CPU with AMD's new architecture. PCI Express in the northbridge, for graphics, is very exciting, but it's their southbridge products that really excite.

It's VT8237 with even more ability, something to shout from the rooftops about. It's maybe VIA's continued flexibility in their core logic, compared to NVIDIA's single-chip approach, that sees VIA have massive market share domination in the AMD64 core logic market. Outselling NVIDIA by nine parts to NVIDIA's one, the southbridge is largely responsible for that.

Summary

I've neglected to throw in pretty chipset diagrams until I get my hands on final hardware for a full discussion, so I hope everything above gives you a clear view about where VIA are going with their mainstream AMD core logic (there's some IGP parts that I'll cover separately, later on). PCI Express is where they're headed, SLI is in their radar and the enthusiast looks like getting something to pair with those new X700 and GeForce 6600 graphics cards, since we all know AMD CPUs are the CPUs of choice for the gamer.

We look forward to retail hardware that implements everything I talked about.

VIA's PT894 and PT894 Pro

While we're enjoying this AMD and PCI Express party, I'll crash it with a quick bit on PT894 and PT894 Pro, VIA's planned Intel chipsets. PT894 broadly mirrors, paired with VT8251, what Intel released recently in their platform shift on Pentium 4. Support for LGA775 CPUs, DDR-II, PCI Express, HD Audio and the like are all in there. However it's the Pro version that caught my eye, implementing the dual PEG16X graphics solution that K8T890 Pro does, just with Intel CPUs. It also brings 1066MHz front side bus support to the table, just like Intel's own i925XE.

VIA are sketchy on details, but it's apparently a Q4 2004 product that's sampling next month. More on PT894 and especially PT894 Pro, as and when we get it.