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Powering the Athlon 64: VIA and nVidia Chipsets Learn how the first production chipsets from VIA and nVidia for the Athlon 64 series differ from previous chipset generations and from each other

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Powering the Athlon 64: VIA and nVidia Chipsets
Learn how the first production chipsets from VIA and nVidia for the Athlon 64 series differ from previous chipset generations and from each other

Powering the Athlon 64: VIA and nVidia Chipsets

The new AMD Athlon 64 and Athlon 64 FX-51 processors, like the AMD Opteron, mark a huge departure from previous processor designs in two ways:

  • 64-bit processing with full-speed backwards compatibility with 32-bit software
  • Integrated DDR memory controller (a feature normally included in the chipsets North Bridge)

Moving the memory controller away from the North Bridge into the processor indicates that the Athlon 64 and 64 FX processors chipsets represent a new paradigm in chipset design. In this article, youll learn how the first production chipsets from VIA and nVidia for the Athlon 64 series differ from previous chipset generations and from each other.

nVidia nForce 3 Return of the One-Chip Chipset

Although weve become accustomed to the notion of a two-chip chipset on typical PCs, in which one chip (typically known as the North Bridge or the Memory Controller Hub) connects to high-speed components such as AGP video and memory and a second chip (South Bridge or I/O Controller Hub) connects to low-speed peripherals, nVidias nForce 3 bucks the tide with a single-chip design.

Single-chip chipsets are nothing new: Silicon Integrated Systems (SiS) has offered several over the years, as I discuss in detail in Upgrading and Repairing PCs, 15th Anniversary Edition. The nForce 3, unlike earlier single-chip designs, benefits from the HyperTransport bus connection between the processor and the chip.

The nForce 3 includes almost every feature commonly included on a typical high-performance system, including:

  • Support for up to six PCI 2.3 busmastering slots
  • Two USB 1.1 and one 2.0 controller (support up to six ports total)
  • AGP 8x
  • 3.6GHz HyperTransport bus (2.4GHz down, 1.2GHz up) connection to processor
  • AC 97 audio with support for up to six channels and 16-bit or enhanced 20-bit sampling
  • S/PDIF audio output
  • ACR and CNR riser card support for soft modem and network connections
  • ATA-133 and SATA hard disk host adapters which support up to six drives total
  • RAID 0 (striping), 1 (mirroring), and 0+1 (striping and mirroring) support for both ATA-133 and SATA drives
  • Integrated Fast Ethernet support, with optional support for Gigabit Ethernet (1000BaseTX) and HomePNA 2.0 (10Mbps) phoneline networks

The only cards you need to add to a system running the nForce 3 chipset include an AGP video card and an IEEE-1394 card (for digital video and some high-speed drives and scanners).

nVidia has also produced a slight variation on the nForce 3 design, call the nForce 3 Pro. The nForce 3 Pro is the Opteron/Athlon 64 FX-51 version of the nForce 3 chipset. Aside from support for these processors dual-channel memory buses, the major features of this chipset are similar to the nForce 3.

VIA K8T800 Modular Design for Future Flexibility

The VIA Technologies K8T800 is a two-chip chipset which has already been used by systems running the Athlon 64s workstation sibling, the AMD Opteron. Most of the features of the K8T800 are similar to the nForce 3, but the K8T800 features support for up to 7.1 (8-channel) audio, compared to 5.1 (6-channel) audio in the nForce 3. VIA also claims that its implementation of the HyperTransport bus eliminates signal interference for maximum speed (when interference exists, HyperTransport negotiates a slower speed to maintain reliable data transport). VIAs implementation of HyperTransport runs at 1.6GHz in both directions (3.2GHz total). As with the nForce 3, motherboards using the K8T800 chipset need only add an AGP card and an IEEE-1394 board (if necessary) to accommodate the latest drives and peripheral devices.

One significant difference is that the separate South Bridge chip used in the K8T800 chip (VIAs VT8237) can be replaced with even more advanced South Bridge chips in the future. The VT8237 is a well-tested design, having already been used in several other VIA chipsets, including the KT600 (Athlon XP) and the new PT800 series for the Pentium 4.

Overclocking Considerations

As Ive written before, Im not a fan of overclocking. However, overclocking is an increasingly popular system-configuration technique, and theres a definite difference between these chipsets when it comes to how well they handle overclocking.

The ability to lock the PCI/AGP bus speeds enables an overclocker to run the processor and memory at higher-than-normal speeds while keeping the PCI and AGP buses at their normal speeds. Because processors and memory often handle overclocking better than PCI and AGP cards do, the lack of this feature in the VIA K8T800 is a big drawback for overclockers. The nForce 3 supports PCI/AGP locking for better stability when overclocking.

Benchmarking the Chipsets

Benchmark tests for both chipsets are widely available online, and despite the difference in design, results are similar. This is most likely due to the lack of a chipset-based memory controller (its in the processor) and the support for AGP 8x graphics.

Consequently, you should look at the specific features of a particular motherboard/system if you are considering the Athlon 64 or Athlon 64 FX-51 processors in your next system upgrade. Some vendors have integrated IEEE-1394a or 1394b controller chips to differentiate the products, or additional management features.

As third-party benchmarks make clear, you should install the latest BIOS upgrades to provide reliable operation of your system.

For Further Review

Vendor Sites

The official website for the VIA K8T800 chipset is located at:

Learn more about the VIA VT8237 South Bridge chips performance with Serial ATA drives at the Via Arena website:

The official website for the nVidia nForce3 chipset is located at

Third-party Motherboard/Chipset Tests

Toms Hardwares tests of the first Athlon 64 and 64 FX-51-based systems reveal some rough edges in early motherboard

Anandtechs test of the Abit KV8-MAX3 shows how the lack of a PCI/AGP bus lock detracts from an otherwise high-performance K8T800-based system

Anandtechs review of the first Athlon 64 motherboards provides a fascinating look at the differences between the chipsets


What kind of HyperTransport performance are you getting if you already have an Athlon 64-based system? No matter what chipset your Athlon 64-series system uses, you can download a free HyperTransport Analyzer from the VIA Arena website:

Copyright©2003 Pearson Education. All rights reserved.

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