The second most significant set of features are the upgrades that have been made in the nForce 4 chipset to the drive controller technology. The controller in the nForce 3 chipset was already one of the more innovative solutions on the market, thanks in part to its 'flexible RAID' support. This time around, the NF4 chipset has received a substantial new feature set.

The new nVidia nForce 4 supports up to 4 SATA drives, and four Parallel ATA (IDE) drives. The serial ATA implementation now uses two separate controllers, each supporting a pair of drives for increased performance.

All drives can be configured into RAID 0, 1 or 0+1 arrays, regardless of which controller they reside on; meaning you can have RAID arrays combining SATA and IDE drives, or use IDE drives as spare fall back disks for SATA RAID arrays.

‘Hot spares’ are supported for RAID 1 or 0+1 arrays, allowing you to have a separate drive installed but unused and designated as a spare. If one of the disks in your RAID array fails, the disk controller will rebuild the array on the fly using the spare disk. To aid in swapping out defective drives, the SATA ports support hot-swapping. All this can be done transparently within the operating system itself.

To add to this comprehensive list of RAID features, the chipset supports RAID ‘morphing’ where one type of RAID array can be converted into another from the operating system. For example, you could convert a RAID 1 array to a RAID 0 stripe, upgrade a RAID 1 mirror to RAID 0+1 (provided two extra drives were attached).

All in all, the new nVidia NF4 chipset adds a huge amount of almost business-calibre RAID functionality to Athlon 64 systems. Although, we’re forced to wonder what users nVidia thinks will actually make use of all this RAID goodness.

This would be a good time to mention that the fourth (as yet) unreleased version of the nForce 4 chipset will apparently be a dual-Opteron based design, with 40 lanes of PCI Express and dual 16x video slots. It looks like we answered our own question, as the nForce 4 chipset is undoubtedly going to be targeted towards business users, and perhaps even servers a bit later in its active life. I doubt it will see much application in servers, industry is usually unwelcome to new and unproven technologies.