..:: Introduction ::..
For several months, the Intel 845PE chipset was one of the highest performance chipsets available for the Pentium 4 processor, up until the more recent chipset releases. When the 845PE chipset debuted, it brought the much needed support for the DDR333 standard, and when placed in unison with the 533MHz FSB Pentium 4’s was hard to beat. This new DDR333 standard was necessary because Intel’s main competitors VIA and SiS had already placed products on the market offering support for DDR333, and sometimes even DDR400. Since the inception of the 845PE chipset, several new technologies have made headway into the mass market such as DDR400 SDRAM, and Serial ATA. The i875P Canterwood chipset brings forth support for Dual Channel DDR400, the new 800MHz Front Side Bus Pentium 4 Processors, Intel’s Performance Acceleration Technology (PAT), the AGP 8X Graphics Interface, a Dedicated Network Bus (DNB), Serial ATA, and more. Today we’ll be examining the i875P chipset, and the Intel D875PBZ motherboard, powered by the new 3.00GHz 800MHZ FSB Pentium 4 processor.
..:: Intel 875P Chipset ::..
The i875P chipset isn’t Intel’s first offering featuring some form of dual channel DDR. The E7205 “Granite Bay” chipset was the first out of the gates from Intel offering such support, but many motherboard manufacturers chose not to adopt the chipset due to the high cost and the relatively short shelf life between the time they could get their products onto the market, and when the new Canterwood and Springdale chipsets would debut. E7205 only allowed for dual channel DDR support up to DDR266 specs since the 533MHz FSB Pentium 4’s were limited to a maximum bandwidth of 4.3 GB/s, the same that the DDR266 solution would provide.
This is where the Canterwood chipset steps into the spotlight. Canterwood allows for dual channel DDR400, 333, and 266 (DDR266 support depends on the motherboard). In turn, the chipset supports both the older 533MHz FSB and the new 800MHz FSB Pentium 4 chips. The new bus speed allows for a maximum bandwidth between the MCH and processor of 6.4GB/s! In order to properly utilize the maximum amount of bandwidth between then MCH and processor, dual channel DDR400 is clearly the way to go since its theoretical maximum bandwidth is, of course, 6.4GB/s. There are of course, some basic requirements if you plan on running the board with a dual channel memory configuration. In order to maximize the system performance, and enable the PAT technology, you must have matched DIMM’s of identical density, DRAM technology, bus width, and an equal amount of memory banks. The memory does not however need to be of the same brand, timing specifications, or DDR speed. If you want to enable the PAT, you'll need to be running an 800MHz Pentium 4, and dual channel DDR400. The i875P chipset also features improvements when it comes to the processor technology.
Canterwood was designed specifically for use with the latest Hyper-Threading enabled Pentium 4 processors. The chipset itself helps to administer and prioritize the various threads that are received from the processor during operation. Since Hyper-Threading will be available on future Pentium 4 chips, and since Intel will eventually be spreading Hyper-Threading support down the line, it is becoming more vital to further improve this technology and make it as effective as possible. We have seen the benefit that can come from the Hyper-Threading Technology, but there must also be software support from the industry in order to properly take advantage of the technology. For those whom may still be unfamiliar with Hyper-Threading, here's some information. This technology effectively makes a single physical processor appear to be two, separate logical processors. Each of these two logical processors shares between them a set of physical execution resources such as caches, execution units, and branch predictors while there is a single copy of the architecture state for each of the logical processors. The “architecture state” consists of the various general purpose registers, controls registers, the APIC registers, and even some machine state registers.
With this technology, software can in effect schedule multiple threads to the two logical processors as they would if it were a multi-processor system with two physical processors. What does this mean when it comes to performance? Well, if the software can take advantage of both logical processors, it can in effect process multiple data threads at once, thereby improving the overall efficiency of the processor. Modern processors can theoretically processes several different instructions per clock, however due to inefficiencies in the pipeline and other nagging problems, the processors are unable to execute the amount of instructions per clock that they are theoretically able to handle. Intel’s Hyper-Threading Technology helps with this problem by making the processor run more efficiently and process more data at once.
The i875P chipset consist of two separate controller hubs, 82875P and 82801EB, as we are used to seeing. The 82875P is the Memory Controller Hub (MCH) that utilizes the latest Performance Acceleration Technology, and offers support for the 800MHz and 533MHz FSB processors. The 82875P also brings forth support for the latest 1.5V AGP 8X graphics adapters. The ICH5 82801EB I/O Hub has dual, independent Serial ATA controllers that provide 150MB/s data transfers between each of the connectors along with Intel’s new RAID Technology. The ICH5 I/O Hub also features support for up to eight high-speed USB 2.0 ports which are backwards compatible with USB 1.1 specifications. The ICH5 also features full support of surround sound audio with dual independent DMA audio engines, and an integrated LAN controller. One of the major features of the i875P chipset which we will be taking a look at next is Intel’s Dedicated Networking Bus, or DNB.