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VIA PT Series Chipsets Overview VIA PT Series Chipsets Overview: Today marks the announcement of VIA's latest entries into the Pentium 4 LGA775 platform. We look at the technology which covers entry level to enthusiast.
Date: January 31, 2005
Written By:

Since the launch of the LGA775 platform last June, Intel have pretty much fended for themselves with their 915P, 925X, and 925XE (and additional variations of the three chipsets). Partnerships were formed with other chipset vendors, but those companies as well as companies with preexisting agreements have been fairly quiet during this time.

PT880 Pro
PT894 Pro

That changes today as VIA Technologies will be announcing not one, but three new chipsets for the Pentium 4 platform, the PT880 Pro, the PT894, and the PT894 Pro. Actually, the last two are really the same thing, but they will cater to different market segments depending on your needs.

The three chipsets will support the Pentium 4 LGA775, and sport all the next-gen things we've come to know and sometimes love; Dual Channel DDR 1 and 2 (667MHz), 1066MHz Quad Pumped Bus, PCI Express, SATA-II, RAID-5 and an interesting graphics technology called DualGFX which we'll get into shortly.

The PT880 Pro

While VIA is classifying the chipset as a budget solution, we're looking at it more as a "transitional" solution from a user standpoint. How so?

For one thing, we're expecting mobo makers to ship boards with a co-layout of DDR1 and DDR2. This is VIA's StepUP Technology and will allow users to keep their DDR1 modules if they have not yet moved to DDR2 which is still priced at a premium. While we can expect a maximum of four DIMM slots, VIA suspects whether users have 512MB, 1GB or even 2GB, chances are it's spread across only two DIMMS. Basically, if you have two DDR sticks, you'll move them over here until the time is right to migrate to DDR2. If you have four sticks, you'll be SOL as you'll need to pawn off a couple of them, unless the manufacturer goes for one memory type on their board.

Unfortunently, those of you dreaming of pairing up two DDR and two DDR2 will need to snap out of it as the chipset will not support two memory types running at the same time.

Though the board should be priced in the same range as Intel's i865PE and i875P, we didn't ask about Socket-478, but our guess is there won't be any support for it. For the LGA775, both 800FSB and 1066FSB will be supported.

Another feature which will appeal to many of you is the board's support for both AGP and PCI Express graphics, known as VIA's Flex Express. The AGP8x slot will be a native connection (no bridge) and should perform as well as a traditional AGP slot. The PCI Express slot will not be the x16 (read: bi-16) that most of us are accustomed to and will be a x4. According to VIA, the x4 connection should not impact performance with today's video cards under most mainstream circumstances. At worse, you may lose 20% of the performance, but that is the tradeoff for having both interfaces handy. Yup, you read that right. It is possible we may see PT880 Pro boards with both AGP8x and PCIe x4 on the same board. Unlike the ram situation, on boards with both graphics interfaces, you can use both at the same time. We'll talk more about DualGFX soon (sorry for keeping all of you in suspense).

The PT894 and PT894 Pro

PT894 Pro

Moving on to the mainstream will be VIA's PT894 chipset. Like the PT880 Pro, the chipset will support up to 1066FSB LGA775 CPUs and both DDR1 and DDR2. DualGFX support will not be present though, as these boards will feature one x16 PCIe slot for discreet graphics.

PT894 Pro

The PT894 Pro will be aimed at the workstation and enthusiast sector, and has the same features as the PT894 except it will support DualGFX. I guess that's enough with the tease...

Introducing DualGFX

With the "Pro" chipsets announced today (the AMD driven K8T890 Pro is also capable of this), users will have the ability to run two discreet graphics cards at the same time. We've already gone over the implementation with the PT880 Pro, which can use one AGP and one x4 PCIe. For the PT894 Pro, there won't be an AGP option so we're talking about two PCIe cards here. It may sound a lot like NVIDIA's Scalable Link Interface (SLI), but other than simply plugging in two video cards into one mainboard, that's where the similarities end.

NVIDIA's implementation works by splitting the PCIe lanes and load balancing for rendering whole sections of a screen at any given time. For supported games, GPUs and motherboards, this can be a huge benefit for gamers. Of course, the dig is you need compatible hardware and software to make this worthwhile.

VIA uses 20 lanes and splits the workload to x16 and x4. While a gamer may scoff at the "x4", the technology isn't targeted at gamers at all, but rather, the workstation market. The DualGFX will allow up to 4 monitors to be connected to a DualGFX enabled PC. For those of you who like to "work" in addition to "play", four screens for workspace is quite a sight to behold.

Granted, NVIDIA does allow 4 monitors to be hooked up as well, but that means turning off SLI to do so. One thing SLI cannot do which the new VIA chipsets can is run AGP and PCIe at the same time. VIA's DualGFX certification seems to be a bit looser as well, so you can have two completely different GPUs on the same board. Also, for Pentium 4 owners, SLI only works on Intel's workstation boards (and those Xeons aren't cheap) so the PT880 Pro and PT894 Pro will provide a more economical path to having multiple screens for your workspace.

We mentioned that the technology isn't really suited for gaming at this time but this could change in the future. It's unlikely that DualGFX will provide any speed benefit, but it can provide productivity in gaming (if that is possible) by allowing scores or game information on one screen, and gameplay on another. While support is limited at the moment, X2 and MS Flight Sim are currently supported by DualGFX.

One thing that gamers may be concerned with is which of the two video cards will be powering their games? Last thing we need in an ATI X850 and ATI 9000 Pro setup is for the 9000 Pro to power your Half-Life 2 game. Thankfully, setting your primary video card is as easy as setting the option in the BIOS.

Finally, for those dead set on NVIDIA SLI, officially both VIA and NVIDIA will tell you it doesn't work on the new boards. In theory, it should work, and in practice, some users have indeed gotten the different technologies to work together. We'll definitely give it a shot once we assemble the hardware.

The VT8251 South Bridge

After what seems like forever, the VT8237 will finally be put out to pasture. While it's still a solid South Bridge, the VT8251 will bring to additional PCI Express lanes, four SATA-II 3GB controllers, and 2 IDE (4 ATA133 devices).

We've mentioned RAID-5 earlier, and as we've discussed in our nForce Professional article, RAID-5 allows both speed and redundancy and is normally a technology found in RAID controllers. It's still going to be expensive to implement on the desktop as three physical drives are needed, but this is something workstation and server users will appreciate. Nonetheless, RAID-0, 1, 0+1 and JBOD will all be supported.

The controller also supports AHCI and NCQ, as well as support for port multipliers. Ever wanted to connect 60 hard drives to your PC? Now you can. Granted, there will be serious bandwidth issues, and you still need a third party port multiplier, but for certain applications, this can be very beneficial.

We should point out that for the official launch, as with the PT894 provided to us for today's coverage, mobo makers will still be packaging the VT8237 with the first batch of boards. Speaking of which, let's take a closer look at the PT894.


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