The IGP

NVIDIA's way: distributed computing

The way NVIDIA sees it, system chipsets have traditionally acted as a connection point between the components within your PC. The CPU, graphics card, and system memory are connected to the North Bridge, which in turn is connected to the South Bridge. The PCI components such as sound and networking are connected to the South Bridge, effectively using both bridges as the "glue" that holds the components within the system together. With nForce, the traditional North Bridge/South Bridge architecture has been replaced by a distributed processing platform that takes some of the load off the CPU.

In theory, all an end user would have to do is plug-in a CPU inside an nForce motherboard to create one powerful PC platform. This is made possible by two components within nForce: the integrated graphics processor and media communications processor.

IGP

The integrated graphics processor, or IGP, performs the role of the North Bridge in a traditional system chipset. It consists of four components: the TwinBank Memory Architecture, the Dynamic Adaptive Speculative Pre-Processor, a GeForce2 GPU, and a HyperTransport interface for communicating with the media communications processor.

nForce diagram

TwinBank Memory Architecture

With TwinBank, the nForce IGP offers up to 4.2GB/sec of bandwidth, twice the amount available on any other chipset available for Athlon. It accomplishes this via its dual independent 64-bit buses, each with its own memory controller. As a result, the CPU and GPU can access memory concurrently, or one or the other can use both memory controllers at once. This allows for the most effective use of the memory bandwidth available.

TBMA in action

For maximum compatibility, end users can mix and match modules of different speeds and sizes. In fact, the IGP can even operate with a single DIMM installed. Of course, if you do this, you will no longer be taking full advantage of the 128-bit TwinBank Memory Architecture, as you'd be operating in 64-bit mode with one controller.

There will be two versions of the IGP that will be split into two segments: performance and mainstream. The performance segment will get the IGP with the 128-bit TwinBank Memory Architecture we described above called the nForce 420, while the mainstream segment will get a stripped-down 64-bit only version of the IGP dubbed nForce 220. We'll discuss some common questions we've received concerning the TwinBank Memory Architecture a little later in this article.