VIA PT880 Chipset Preview

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

By: Chris Angelini
December 8, 2003

Reference motherboards are interesting creatures. Chipset manufacturers, such as VIA, SiS, ALi, NVIDIA, and ATI, all design actual products to showcase their core logic technologies.  Thus, the reference boards are most often fully featured versions of what a third-party manufacturer could do if they wanted to go all out.  VIA's VT5798B is no exception - every feature listed on the PT880 specification sheet is present and accounted for, in addition to a few extras that aren't mentioned.  That being said, reference boards can be pretty quirky, especially since they aren't meant for retail consumption.  We've been testing two PT880 boards - one on the east coast and another on the west - and it should be noted that the board used for benchmarking failed to load Windows XP properly over any Serial ATA hard drive.  Consequently, we used an older IBM ATA-133 drive for testing. 

Other than the slight Serial ATA glitch, our reference board behaved well.  It features four 184-DIMM slots for up to 8GB of DDR400 memory, and of course, a Socket 478 interface with full support for an 800MHz front side bus.  During VIA's visit, we inquired about proper Prescott support, the code name for an upcoming revision to the Pentium 4 architecture.  The VIA representative wasn't sure, mainly because Prescott processors seem to be in particularly short supply, even to hardware vendors designing the supporting infrastructure.  So, it remains to be seen whether Prescott will run flawlessly on PT880.

Layout is a bit of an issue for the PT880 reference board.  Hopefully, manufacturers opt to move the power connectors from below the socket interface, where they are now, to the far right of the board to aid in air circulation.  Also, the board's lone parallel IDE connector lies directly under the AGP slot.  While we didn't encounter any problems with our RADEON 9800 XT, a longer card could potentially necessitate some adjusting of the IDE cable.  Again, this is probably one area where third-party manufacturers will choose to do a bit of redesigning.  Indeed, a quick look at MSI's PT880 Neo-FISR reveals that both recommendations are being addressed.

The board's back panel gives a pretty good indication of what the PT880 chipset can do.  Beyond standard PS/2, serial, and parallel ports, it boasts four USB 2.0 ports and two RJ-45 connectors, one of which interfaces with a VT6103 10/100 PHY, while the other offers 10/100/1000 Gigabit Ethernet through the onboard VIA Velocity controller.  There are also two stacks of three, 1/8" analog mini-plugs for connecting eight speakers, a microphone, and a line output.

A few words are in order for both the integrated Ethernet and audio solutions.  One reason for improving throughput over the V-Link bus, we surmise, is to improve performance of Gigabit Ethernet transfers. VIA doesn't offer an equivalent to Intel's CSA architecture, which stems from the 875P's Memory Controller Hub (MCH).  Instead, VIA's Gigabit solution connects through the VT8237 South Bridge.  The VT6120 chip present on our reference board features Cicada Semiconductor's SimpliPHY technology, which Cicada uses in its own 8200 series of Gigabit transceivers.  The 196-pin LBGA chip communicates over the PCI bus, which would suggest a performance disadvantage.  However, even while VIA found that Intel's 82544 Gigabit controller transmitted at a higher throughput, its own VT6120 did better on the receiving end.  The most tangible benefit of its controller, though, according to representatives at VIA, is effective cable reach.  Gigabit Ethernet is highly susceptible to signal noise.  So, under poor conditions, competing solutions can be reduced to as little as 10 meters of reach.  Under the same circumstance, the Velocity controller maintained 150 meters of reach. 

Another of the PT880 reference board's strong suits is its audio implementation.  Lately, we've spent a lot of time testing small form-factor systems, including Shuttle's SB65G2 and SN85G4 XPCs.  The allure of a fully featured chassis is undeniable.  These systems offer audio, video, and networking all in one compact package.  However, subjective listening tests on both Shuttle's SB61G2 and Biostar's iDEQ 200N have exposed quite a bit of distracting background hiss due to noisy signals.  Using a set of standard multimedia speakers, the hiss might not be noticeable.  But Sennheiser's HD600 headphones are of high enough quality to observe the problem immediately.  Simply, integrated audio needs to be implemented carefully in order to avoid crummy sound quality.  The PT880 reference board employs VIA's Envy24PT entry-level controller and a VT1616 "Six-TRAC" codec for six-channel output.  It isn't the highest-end configuration VIA offers (that'd be the Envy24 and VT1617 codec), but it is sufficient so that the board's audio outputs aren't muddied by electrical noise.  After suffering through several quality recordings played back on competing integrated controllers, the Envy24PT/VT1616 combination is refreshing. 

Of course, the VT8237 South Bridge natively supports two channels of Serial ATA connectivity, but enabling RAID 0+1 requires two more.  An integrated VT6420 Serial ATA RAID controller contributes the extra channels, and a Silicon Image PHY adds an additional pair, for six total channels of Serial ATA.  Not all manufacturers will follow suit, though.  The aforementioned MSI board, for example, comes equipped with four channels of Serial ATA. 

The reference board includes one AGP 8x slot and three PCI slots, which again, is not representative of a third-party configuration.  MSI's PT880 sports five PCI slots, though given the PT880's degree of integration, extra PCI slots shouldn't even be necessary.

Specifications of VIA's PT880 Reference Motherboard Third-Party Boards WILL Vary

The BIOS:

We'd expect that most retail PT880 motherboards won't feature the exact same BIOS found on our reference board.  Even still, it's good to know that the chipset is highly flexible.  Third-party manufacturers looking to coax extra performance from the chipset should find it an easy task.  Similarly, resourceful enthusiasts can expect plenty of options for tweaking every aspect of the platform's operation. 

Front side bus frequencies are selectable in 1MHz increment, for instance.  Or, if you'd like to overclock your AGP and PCI devices, you can choose between a number of settings.  The Ultra V-Link interconnect can even be adjusted.  A whole host of memory timing adjustments have been exposed in the DRAM Clock menu and voltages can be set independently for CPU (1.625-1.775V), DDR (2.65-2.75), and AGP. 

Check out the screenshots above for a smattering of what the PT880, in its current form, is capable of. 

How We Tested and SiSoft's Sandra 2004