Motherboard Guide

ULi M1695 HyperTransport PCI Express Tunnel Chip

ULi M1695 HyperTransport PCI Express Tunnel Chip



Express Power - The M1695

Express Power - The M1695

So what's all this fuss about another AMD Athlon 64 chipset? Considering that the market has more or less been cornered by NVIDIA and their successful nForce4 series, what has ULi's M1695 to offer that caused heads to turn and ripples to form? Let us first take a glimpse at how NVIDIA has planned their strategy. From the nForce4 onwards, NVIDIA has focused on providing the very best, pushing out the highest end SLI chipsets first to capture market share before releasing their mainstream solutions. This is the same strategy that they've employed for the Intel version of the nForce4 and the recent release of their GeForce 7800 GTX GPU. The nForce4 has been built first and foremost with the enthusiasts in mind, filling it with the latest and greatest of features, including Gigabit LAN, ActiveArmor hardware firewall and of course (re-)introducing SLI technology. This has put NVIDIA on the top with competitors trying to match products

ULi's approach is less grandiose, though no less as exciting. The M1695 intends to make its mark on the Athlon 64 market and the ace up ULi's sleeve is in flexibility, a whole bucket load of it. Instead of going head-on with NVIDIA in terms of high-end features, the M1695 boasts a broad range support of technology and is probably one of (if not the most) adaptable chips at present. In the past, chipset interconnects have mostly been of a proprietary nature, such as VIA's V-Link and Intel's DMI. ATI's latest Radeon Xpress 200 is more technology friendly with their A-Link Express interconnect, which basically uses the PCI Express bus. However, ULi went one step further to design the M1695 as a HyperTransport tunnel chip. The HyperTransport protocol is a relatively more open technology, widely available, easy to implement and offers high throughput. It is probably most recognizable as the interconnect for AMD Athlon 64 processors. The use of HyperTransport in the M1695 allows the chip to practically form connections with a wide variety of downstream components to increase its functionality and support.

As an Athlon 64 chipset, the M1695 in itself is an incredibly simple component. Since the memory controller is on the CPU, the M1695 has only two functions. Firstly, it is a HyperTransport tunnel offering full 16bit upstream and downstream links between CPU and downstream (Southbridge) devices. Secondly, it provides PCI Express support. That's basically it. The chip supports up to 20 PCI Express lanes split into three possible ports. ULi's whitepaper suggests that the possible configurations for the PCI Express lanes are 16+4, 16+2+2 or 8+8+4. This specification is interesting indeed as the 8+8+4 configuration would mean that the M1695 can support dual PCIe graphics and even SLI setups. We wouldn't rule out the fact that you can even install three PCIe graphics cards, provided that the correct physical slots are available on the board. The block diagram above basically represents the basic M1965 connectivity and features.

Besides the ultra-simplistic HyperTransport tunnel interface, the M1695 boasts another feature called Triple Graphics Interface (TGi). This is ULi's way of telling us that the M1695 can support AGP, PCI Express and PCI graphics concurrently. No big deal you might say. There are already motherboards that provide support for both PCIe and AGP graphics interfaces you might think; and you would be right. However, previous attempts to offer AGP on a PCI Express chipset were mainly based on AGP bridges running on top of the PCI bus. Thus, they were greatly performance limited. The M1695 on the other hand, can lay claim to be the first chipset that offers a full speed, full performance AGP 8X port in addition to a PCIe x16 (or dual PCIe x8) and even a traditional PCI card. This little menage trios is made possible through the use of ULi's M1567 companion Southbridge. Possibly the most common configuration for the M1695, the M1567 is a new HyperTransport Southbridge that offers your standard array of features such as onboard audio, LAN, USB 2.0, SATA and of course the AGP 8X port. The following table shows the general specifications of the M1567 Southbridge. Though you might think that the M1567 is nothing to shout about in terms of advanced features, remember that it was basically designed to enable TGi for the M1695 than anything else.

ULi M1567 Southbridge Feature Set
HyperTransport Interface
  • Bi-directional 16x8 bus width
  • 800MHz HyperTransport clock speed
  • 4.8GB/s total bandwidth
AGP Interface
  • Supports one AGP 8X port
Storage
  • 4 x Ultra ATA 33/66/100/133 (data transfer rate up to 133MB/sec.)
  • 2 x SATA (Serial ATA 1.5Gbps interface)
USB 2.0
  • Supports 8 USB 2.0 ports
  • Supports High Speed transfers (480Mbps) and backward compatible with Full Speed (12Mbps)
PCI Interface
  • PCI 2.3-compliant>/li>
  • Supports six PCI Masters
Audio
  • AC'97 compliant sound controller
  • Supports up to 8 or 6 channels of audio (dependant on audio codec)
Networking
  • Built-in Fast Ethernet (10/100Mbps) MAC
Legacy I/O
  • LPC Super I/O bus