Intel 875P (Canterwood) Chipset - The New Flagship

A New ICH

If you haven't gotten the hint already, Intel went all-out with the 875P and the trend continues with the chipset's new I/O Controller Hub - ICH5.

There are two major features of ICH5 that separate it from its predecessor, ICH4; the first feature is integrated support for a total of 8 USB 2.0 ports. Intel claims that this is the last time they will be upping the number of USB ports supported as 8 seems to meet the current and foreseeable demand.

The next and quite possibly the most important feature of ICH5 is its integrated Serial ATA controller. Current Serial ATA controllers use a PCI interface to the South Bridge (or MCH) and thus eat into the 133MB/s of bandwidth that is allocated to the collection of all 32-bit 33MHz PCI slots on a motherboard. Well, if you look at the Serial ATA specification you'll notice that the maximum transfer rate is listed as 150MB/s, that's 13% more bandwidth than a 32-bit/33MHz PCI bus can provide! Whether or not drives are currently reaching even half of that maximum transfer rate isn't an issue, regardless of what the case is, you never want to create additional bottlenecks; by placing the Serial ATA controller off of the PCI bus, a bottleneck is created that would only be exposed down the road.

Intel's ICH5 gets around this problem by bringing the Serial ATA controller onto the ICH and bypassing the PCI bus all together. The Serial ATA controller has a direct link to the Hub Link 2.0 interface in ICH5 and thus can offer a full 150MB/s per channel. ICH5 features two Serial ATA channels (supporting a maximum of two drives) and two Parallel ATA channels (supporting a maximum of four drives), all of which may be enabled and used concurrently.

Because ICH5 is so new, there is no support for the chip in Intel's Application Accelerator drivers, which is why some I/O intensive benchmarks will show the 875P platform as performing much worse than it should be. Hopefully Intel will remedy this situation as quickly as possible, as it really is quite disappointing to see a brand new platform like the 875P not performing to the best of its potential due to driver limitations.