The 875P Northbridge supports AGP 8X and with this Intel is finally meeting the demands of graphics card manufacturers and the requests orf the enthusiasts. The chip is produced using 250 nanometre technologies. While having 1005 soldering balls on the underside of the chip, the size of the chip is no larger than that of the E7205.
The smaller but chunkier model achieves a power dissipation of approx 11 watts with an FSB of 200 MHz. At least the Canterwood Northbridge has only passive cooling on the Intel Reference board. However, some motherboard manufacturers still prefer to use fan-cooled solutions. Gigabyte and ABIT have taken up the active cooling solution.
Memory and PAT
The memory controller on the I875P is a new generation controller. Using technology first introduced by nVidia nFroce chipsets, Intel uses a 128bit Dual Channel DDR memory controller. Supporting two channels for up to 4GB in four DIMM slots, Intel achieves a Dual Channel Architecture that is equivalent to that used by the nForce 2.
One rather unexpected surprise on the I875P chipset is the inclusion of official DDR 400 support. Normally Intel has waited for JEDEC to support a standard before it adopts it; after all it took quite a while after JEDEC adopted DDR-333. DDR-400 memory alone in single channel supports a max theoretical bandwidth of 3.2GB/s, using Dual Channel you get 6.4GB/s, the same bandwidth speed that the 800Mhz FSB P4 is able to generate.
Performance Acceleration Technology
Intel uses a small trick in order to squeeze an extra drop out of the MCH. Through an improvement in the logic design, the manufacturer has succeeded in saving one cycle when the CPU requests to perform a memory access, and a further cycle with the DRAM Chip Select. However, this only works with the 875 and 200 MHz FSB. The Springdale does not have PAT. Generally, the selection process for the Canterwood and Springdale chipsets is made based on "Speed Binning," as it is already known in the fabrication process of CPUs. If the silicon does not meet the requirements of the Canterwood qualification, such as PAT, then it can only be put through the Springdale qualification test. The chip makes a trip to the garbage bin only when it fails both of the tests.
CSA - The new Bus
Gigabit Ethernet is slowly becoming the new standard for Ethernet. Most motherboard companies are now integrating Gigabit Ethernet controllers onto their motherboards. Gigabit Ethernet allows 1000 megabit along standard Cat5E Ethernet cable. This is a great increase in bandwidth but this comes at a price. Using the PCI interface increases a bottleneck on the PCI bus. With other devices like RAID and Sound systems the PCI bus can'tt handle the increased load of gigabit Ethernet. Intel'ts latest approach is to incorporate a new bus directly into the Northbridge. The Communications System Architecture or CSA is a second hublink architecture running at 266MB/s, similar to the PCI64 bandwidth. This allows for a direct connection to the Northbridge.
The Intel I/O Controller Hub version 5 is the newest controller chip designed to work with the I875P and I865 chipsets. 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 current and future demand.
The next, and by far the most important feature is the Native support for Serial ATA. Up till now, if you wanted Serial ATA you needed to have a Promise, Highpoint or Silicon Image Serial ATA controller chip. Intel is the first of the Chipset manufacturers to have a Serial ATA controller built into its Southbridge. VIA has announced the VT8237 Southbridge, however, this chip has not made a show on the market. If you look at the Serial ATA specification, you'tll notice that the maximum transfer rate is listed as 150MB/s, that is 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'tt 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'ts 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.
Intel also gives another reason to say goodbye to third party SATA controllers with the inclusion of RAID function in the ICH5R version. This allows you to use RAID 0 or 1 on the Serial ATA drives connected to the ICH5R.