The AMD 890FX Chipset

The AMD 890FX Chipset

So to understand the 890FX chipset from AMD, aimed at the more enthusiast crowd, all we simply need to do is tell you a thing or two about it's features. The 890FX chipset consists out of two chips that are added onto the motherboard PCB. The Northbridge chip, which is called the 890FX and the paired (Southbridge chip) SB850. Together they form the infrastructure for all standard devices, connectivity and interconnect bandwidth.
The Northbridge chip primarily functions as a HUB for your processor, memory and PCIe links towards your graphics chipset. It is the primary chip responsible for these functions, the FX (opposed to GX) extension however indicates that there is no IGP embedded into this ASIC which the GX versions do have.

The 890GX has many PCIe link available for your dedicated graphics (or other add-in cards). The chipset allows you to utilize two full x16 graphics cards, or even four graphics cars as they would run at x8 PCIe links.

Now believe it or now, but there's more than the 890GX and FX chipsets as AMD today also launches the 870 and  880G chipset. Below you can find a little chart showing the difference without hogging up a full page with explanations.

As stated this chipset also includes native support for SATA 6Gb/s for aggressive RAID and SSD configurations and most motherboards are expected to include USB 3.0 support employing the chipsets dedicated PCI express link and leading discrete USB 3.0 solutions.

New in the 890 FX chipset, is IOMMU support. Not something that the majority of you guys would be interested in but it allows for virtual addressing of memory by system devices. This enables devices to use their native drivers in a virtualized environment for enhanced performance. In a non-virtualized environment, IOMMU provides memory isolation and protection capabilities - device access to system memory is vetted by the IOMMU such that critical/unrelated memory information (e.g. kernel pages, protected content ) can be protected, leading overall to a more robust system. With an updated Hyperlink (revision 3) we now can connect to the SB850 chip with a well-appointed 2GB/sec bandwidth (full-duplex). Let's have a look at the SB850 Southbridge chip.

The SB850 Southbridge

The new Southbridge is a nice update over the older SB7x0 series. The Southbridge ASIC is always used for peripheral connectivity like your HDDs, audio, USB, PATA and so on.  The biggest changes then. Well firstly, we see the first chipset vendor actually implementing SATA 6G (SATA3), this new update of your SATA connectors will increase the bandwidth on the SATA controller from 3 towards 6 GBit/sec. Now for regular HDDs that is not really very important. But with the tremendous rise of fast SSD drives this really is a large plus. Typically we get 3000 Mbit/s : 8 = 375 MB/sec bandwidth minus tolerances and random occurrences. SATA3 is doubling it up, as such we get 6000 Mbit/sec : 8 = 750 MB/sec of available bandwidth for your storage devices. As you can understand, with SSDs getting faster and faster that's just a much warmed and welcomed increase of bandwidth. Also do not forget RAID performance, which can see massive benefits of the updated SATA interface.

There's more to the SB850 though, it will now allow you to connect up-to 14 USB 2.0 devices, of course comes with support for PATA and 8 channel HD Audio and the old fashioned PCI interface, but new is the inclusion of a 1000/100/10 Mbit/s Ethernet. And all these facts combined, allow any ODM to make a very diverse motherboard with the usage of just the AMD 890GX chipset. Literally, you pop in memory, a processor, an HDD and a PSU and you'd already have a fully functional and extremely diverse PC. So with the new chipset, AMD can address any market whether that is entry level, mainstream or when you pop in high-speed DDR3 and a dedicated graphics card ... high-end.

With the chipset out of the way .. it's time to focus on the ASUS Crosshair IV Formula motherboard itself.