Chipping in

In the last issue of Windows we reported on the launch of AMD's new ‘Spider' PC enthusiast and gaming platform. Spider is made up of three core components: any member of the Phenom 9000 series of quad-core processors, a GPU from the Radeon HD 3800 family, and any Northbridge core-logic 700 series chipset.

The latter core-logic chipset is responsible for connecting each and every device attached to your PC to one another. Most chipsets actually comprise two chips; a Northbridge and a Southbridge. These chips are each connected to a certain set of components; the system's core components such as the processor, memory and graphics card are usually connected to the Northbridge chip, whereas storage devices such as hard drives, optical drives and USB ports are attached to the Southbridge.

Both North- and Southbridge chips communicate with each other via a high-speed electrical connection, known as a bus, that runs - or drives - along the motherboard's printed circuit board (PCB). This connection is used by the North and Suth bridges to exchange data and is also how devices connected to each bridge communicate with each other.

To date AMD has released three Northbridge chips for its new 700 chipset family: the 790FX, 790X and the 770. The 790FX is the top-end model, whereas the 790X and 770 are designed for the mid-range and entry-level market segments. These three Northbridge chips are differentiated by the support and scalability they offer.

The 790FX, being the top model, features support for up to two CPU sockets, meaning we could potentially see dual-socket motherboards in the near future. Note: This is the only Northbridge to date from this new family to support dual sockets. The 790FX supports up to four graphics cards, which can be run either as individual cards, thus allowing up to eight monitors to be connected simultaneously, or in CrossFireX multi-GPU mode to boost graphics performance (read about this in detail on the next page). With regards the 790X and 770, the former supports the running of up to two cards in CrossFire mode, whereas the latter is designed to work with only a single graphics card.(Check out the table on the right for our scalability comparison.

These differences aside, the three Northbridges also have a number of similarities. The most important of these are support for the HyperTransport 3.0 and PCI Express 2.0 bus specifications, along with support for AMD's automatic overclocking utility, known as ‘OverDrive'.

Technology top-up

HyperTransport, formerly known as LDT (Lightning Data Transport), is a low latency point-to-point, high bandwidth link that can be implemented in serial mode - where data is transferred bit by bit - or in parallel mode - where up to several bits of data are transported simultaneously. It's designed to replace the older front-side bus and offers faster data transfer rates and more expansion flexibility.