The K7N420 uses a rather wasted layout in my opinion. The picture above shows just how the nForce offering from MSI is set up. You can see that it uses a 1/5/1 (AGP/PCI/Riser) layout, but between the AGP and the first PCI slot here is a huge gap that could have been filled with another PCI slot to give a total of 6 PCI. MSI has also elected to go with the standard CNR slot. While nForce has support for ACR, MSI has elected to stay away from this technology for some reason. While most of us don't care for the idea of software driven devices, the ACR supports extra features such as built in DSL capabilities that the CNR based boards do not.
- The nForce itself
Driving the K7N420 is nVidia's very first platform solution, formally known as the "Crush 12"; or now known as the nForce. The nForce consists of the IGP128 Northbridge which hosts a new memory design which has been named "Twin Bank" memory bus. This new memory bus is similar in design to how old SIMM memory used to work. Using two identical memory modules (size, density) you are able to boost the memory bus from 64-bit to 128-bit. This results in 4.2GB/s of total memory bandwidth when using PC2100 DDR SDRAM, or even 5.4GB/s when using PC2700 memory. While the nForce isn't an offical chipset of PC2700, the idea of that much memory bandwidth is very enticing. This is definately a good idea for Pentium 4, but for now its AMD Athlon only.
Along with the new memory bus, nVidia has also integrated into the Northbridge a Geforce 2MX 400 video accelerator. This is the fastest integrated video platform we have ever seen. The onboard video is a Share Memory system which means that it uses system memory for the VGA frame buffer. This does limit the speed of the video card a bit, but with over 4GB of memory bandwidth, you do have some leeway. We will see if it helps out later on.
The Southbridge of the nForce is the MCP-D. This Southbridge brings with it ATA-100 IDE, 6 USB ports, 5.1 Dolby Digital AC'97 Audio and Fast 10/100 NIC. This is also the first chipset to use AMD's HyperTransport Technology to interconect the North and South bridges giving 800MB/s bandwidth between the two; thats more than 2x the VIA V-Link 266MB/s.