I/O Controller Hub
It was with the I875P generation of chipsets that arrived the first of Intel's native SATA supported Southbridges which gave the ICH5 series the achievement of being the first to market SATA Southbridge. Despite Intel's past ICH's being behind the competitors in Southbridge additions, Intel managed to bring Serial ATA and eight USB 2.0 ports out first.
ICH5 now has taken the back seat on the Intel roadmap with a brand new ICH series making its debut on the I9xx series chipsets, dubbed the ICH6 series; it truly is the latest evolution in Southbridges, for the following reasons.
- Increased Bus Bandwidth
Ever since Intel moved from connecting the North and Southbridges through the PCI bus, Intel has used what it dubbed the Intel Hub Architecture. This was a proprietary designed link used between the MCH (or Memory Controller Hub) and the ICH or I/O Controller Hub. This connection has remained at a standard speed of 266MB/s. While fast in its introduction, with ATA-100 HDD and PCI able to take use of 90% of the bandwidth, ICH5 pushed the 266MB/s to the limit with two 150MB/s SATA ports.
The new ICH6 series uses an all new interface running at 2.0GB/s which officially makes the ICH6 the fastest and most bandwidth rich link interface currently available. This new link has been named the DMI (or Digital Media Interface).
- More Serial ATA ports
The Serial ATA system has also been given a full upgrade. Intel has moved from SATA 1.0 specifications to add a new system which is called Matrix RAID Technology.
With Matrix RAID, we have two additional Serial ATA ports for a grand total of four. It seems Intel is urging the market to move away from Parallel ATA since the ICH6 only supports one Parallel ATA channel - a maximum of only two IDE devices are supported on the ICH6 series.
- HD Audio
One of the most evolving parts of the integrated society that motherboards are now becoming is quality onboard Audio. While AC'97 has improved somewhat, it is still CPU hungry, and lacking in the Dolby Digital certifications that nVidia's MCP's was able to obtain.
With VIA's Envy 24 and Creative's Audigy2 pushing the barrier of audio to 24bit and at 192Khz, AC'97 simple isn't robust enough for today's demanding market. Intel has put an end to its AC'97 audio standards and has pushed out a brand new audio system called Intel High Definition Audio or "Azalia" as it's known.
This new standard incorporates 8 channel audio output for up to 7.1 independent speakers, 24bit audio running at 192Khz - in fact, it is identical in standards to the Audigy2 and VIA Envy, only it is built directly into the ICH. This new audio standard has Dolby Digital, THX and DTS approval allowing for a much more vibrant audio experience without the need of buying a standalone soundcard.
- Goodbye PCI!
The last major improvement on the Intel ICH hit list is the PCI bus, or we should say the phasing out of the traditional PCI bus. PCI Express (or PCI-E) is now the hot standard to replace the aging shared 133MB/s bus which has been around since the late 486 stages. Allowing 133MB/s was great when the 486 and original Pentium processor was in its prime, graphics cards which mostly populated the bus could only use a fraction of this bandwidth.
Today we have RAID controller cards, PCI sound cards, gigabit network cards and TV tuner cards all sharing the same 133MB/s. Now an ATA-100 IDE RAID array can eat up close to 80MB/s of that in one go - with the rest of the bandwidth going towards the other cards, it is simply isn't a viable option anymore. PCI-X and PCI64 arrived in server markets to offer greater bandwidth, but are simply too expensive to implement on the desktop.
PCI Express is the answer. PCI-E starts off at 1x with a bandwidth of 500MB/s. PCI-E 16x is used for the graphics card which is simply the same bus but using 16 lanes to get the full 8GB/s of bandwidth.
Intel has place four PCI-E 1x lanes on the ICH6 Southbridges as well as a six PCI master PCU bus. This allows you to have PCI-E slots and PCI slots on the same motherboard. You will start to see these new slots arrive on motherboards, and the variety of cards for it will simply be amazing in the months ahead.
Another feature of PCI-E is that it's an independent bus - that is, each PCI-E 1x port has 500MB/s of dedicated bandwidth for itself. This means that each card can transmit its data to the ICH rather than have to wait in queue on the PCI bus to transmit it data as the older standard required. This will reduce latencies for Gigabit Ethernet, TV Tuners, RAID controllers and soundcards.