760 MPX Chipset

Some changes

This time around, AMD is accompanied by an entire army of motherboard manufacturers producing 760 MPX solutions. Just about all the big players are participating this time around so it’ll be much easier for you to find a dual Athlon motherboard on retail shelves than it was a few months ago. And because there are many more selections to choose from, prices will also be low and they will also fall more rapidly. It’ll be much more difficult for Tyan to ride the wave it has been on this time around while in another respect, it will also be difficult for others to position their boards better than Tyan’s proven product. With that said, let’s take a long at what makes a 760 MPX chipset.

760 MPX Architecture

762 Northbridge Specifications

• Two 266 MHz point-to-point AMD system buses, providing uni-processor or two-way symmetric multiprocessor capability
  
• PC2100 DDR (Double Data Rate) Memory Controller with support for up to 4 GB of memory space (supports four Registered DIMM slots)
  
• AGP-4X Interface (supporting 1X and 2X modes)
  
• Dual Mode PCI 2.2-Compliant PCI Bus Interface
  
• 66-MHz clock with 32-bit and 64-bit data path support (supports up to two PCI slots3)
  
• 33-MHz clock with 32-bit and 64-bit data path support (supports up to seven PCI devices4)
  
• A 949-pin Ceramic Column Grid Array (CCGA) package
  
• 2.5 V Core

768 Southbridge Specifications

• Dual high-speed 266 MHz AMD Athlon system buses, supporting up to two processors
  
• PC2100 DDR memory subsystem supporting up to 4 GB of memory
  
• AGP-4X Graphics Interface (supports 1X and 2X modes)
  
• Primary PCI 2.2 compliant 66-MHz/64-bit/32-bit PCI Bus
  
• Secondary PCI 2.2 compliant 33-MHz/32-bit PCI Bus
  
• Two-channel ATA 33/66/100 support
  
• LPC bus
  
• Thirty-two general-purpose IO (GPIO) pins
  
• USB OHCI host controller supporting four ports
  
• SM-Bus
  
• IOAPIC support
  
• Serial IRQ support
  
• Power Management support
  
• AC ‘97 Audio support

Compared to the older 760 MP chipset, the only thing that has changed moving to 760 MPX is the southbridge and its support for 66MHz PCI slots rather than just 33MHz slots. The 66MHz are also 64-bit and operate at either 3.3 volts (according to PCI specifications) and or 5 volts (for compatibility).

Upfront issues

Unfortunately, we’re going to have to cut through the flashing lights of glory and reveal the ugly side of things. Could AMD be back to its old clumsy ways when it produced mediocre processors in the K5/6 days? We hope not, but we can’t help be feel that there are things that AMD needs to think about.

We’ll be honest about it – the 760 MPX chipset has issues. The most glaring one is that the USB controller in the 768 southbridge behaves oddly. Sometimes it works (rarely) and other times it acts like it’s not even there. Basically, the feature is broken and manufacturers are packaging USB 1.0 and 2.0 cards with their boards. While this isn’t the most elegant fix, there were no other choices as AMD had discovered the malfunction too far into production and couldn’t produce new chip revisions in time for board manufacturers to integrate. Unfortunately, we wish that this was the only issue we experienced while working with 760 MPX based boards as you’ll see in the next few pages.