First of all, I would like to point out that the new nForce4 family of chipsets for the Athlon 64 platform is a further development of the nForce3 Ultra chipset which earned a widest recognition among the users. The main innovation introduced in the nForce4 is of course the support of the PCI Express bus. Besides that, however, there are a few more surprises in the nForce4 .

The implementation of the PCI Express bus in NVIDIA’s new chipset is determined by the architecture of the latter. By the way, the nForce4 is a single-chip solution: the traditional North and South Bridges are combined in one chip. It’s possible because in Athlon 64 systems the memory controller is located in the CPU.

As a result, there’s no additional bus that links the Bridges and limits the data-transfer speed between its controllers, so the chipset-integrated controllers of the nForce4 interact more effectively than in two-chip chipsets.

The second advantage of the single-chip solution comes directly from the fact that the PCI Express lines are implemented via one single controller. In the competing solutions, different chips are responsible for the support of PCI Express x16 and PCI Express x1 buses, but in the nForce4 – one controller manages all of them. As a result, nForce4 appears more flexible in configuring the supported 20 PCI Express lines. Particularly, the mainboard makers can theoretically refuse to implement PCI Express x1 buses, but join them into a PCI Express x4 bus, or split the PCI Express x16 bus into two x8 ones. So, the nForce4 has many surprises up the sleeve for us, one of which is its ability to support more than one graphics card with the PCI Express interface (the so-called Scalable Link Interface or SLI mode).

Another innovation in the nForce4, which makes it one of the most advanced chipsets in the market today, is the second-generation hard disk drive controller. The controller supports four Parallel ATA and four Serial ATA channels simultaneously – none of the competing chipsets can boast the same. nForce4 is also the first chipset to almost fully support the Serial ATA II specification and features like “hot swapping” and Native Command Queuing, and an interface bandwidth up to 3Gbit/s. So, nForce4 is ready for the arrival of the next generation of hard disk drives.

nForce4 has also made some progress as far as RAID arrays are concerned. Particularly, it supports RAID levels 0, 1 and 0+1, which can be made up of drives with any interface, including Parallel ATA. The array can be managed from Windows with the help of a special utility called nvRAID.

Note also that the hard disk drive controller integrated into the nForce4 chipset has a kind of dual-channel architecture as it connects to the chipset arbiter along two independent buses. It ensures higher bandwidth and smaller latencies when the processor is intensively working with the disk subsystem.

NVIDIA has also increased the number of USB 2.0 ports in its new system logic: ten ports are available now against eight they used to have before.