VIA Responds with KT400A, Five Months Later

New Southbridge - Not yet Ready

With the KT400A VIA will eventually be introducing a new South Bridge (VT8237) sometime in Q2, however until then all KT400A motherboards will be based on the current VT8235CE South Bridge - the KT400 South Bridge.

The VT8237 South Bridge will offer native Serial ATA support, which is its main claim to fame. Native Serial ATA support means that instead of having a discrete Serial ATA controller running on the PCI bus, the Serial ATA controller will be integrated into the South Bridge and will not reside on the PCI bus, meaning that it won't be confined by the PCI bus' limited 133MB/s of bandwidth (although current drives are no where near reaching those limits). Intel will also have native Serial ATA support with their ICH5 due out in Q2 with their 865 & 875 chipsets.

The VT8237 also expands the number of USB ports supported from 6 to a total of 8 USB 2.0 ports, which will probably be the stopping point for both Intel and VIA for quite some time. Now it's up to motherboard manufacturers to make sure we have enough headers and enough ports on board to take advantage of what the South Bridges will offer.

The new VT8237 is supposed to be pin-compatible with the current VT8235CE South Bridge, however the presence of a Serial ATA interface on the new South Bridge makes us wonder if maintaining pin compatibility is possible, after all you do need the new interface pins for the two Serial ATA channels on the South Bridge.

The final improvement to the VT8237 South Bridge is support for VIA's Ultra V-Link interconnect, which doubles the North/South Bridge bandwidth to 1.06GB/s. This won't be a performance improving technology since we're not even coming close to saturating the 533MB/s of the present day V-Link interconnect, but it's not too difficult to implement and is definitely a marketing plus.

The VT8237 uses the same 6-channel audio controller that's present in the current VT8235CE South Bridge, although VIA is showing off a higher quality DAC with their VT1616 AC'97 codec that resides outside of the chipset. VIA is claiming superiority to nForce2 with their VT1616, however that's not exactly a valid comparison as the VT1616's counterpart on nForce2 motherboards is the ALC650 AC'97 codec that we see on most motherboards. In theory, a nForce2 motherboard maker could use the same VT1616 AC'97 codec on a nForce2 motherboard. VIA does not have the same processing power of the nForce2's APU because of the lack of dedicated DSP logic in the South Bridge, however as we've seen, the processing power in the nForce2 APU goes unused in most usage scenarios. What it all boils down to in the end is that VIA has a potentially higher quality AC'97 codec than Realtek, which happens to be on most nForce2 motherboards.