New Chipsets: Intel 875 and Intel 865

As we have already said above, new Pentium 4 3.0GHz processors launched today do not boast anything new from the technological point of view. The core they are based on remained the same: it is the same good old Northwood, which is used in Pentium 4 3.06GHz with Hyper-Threading support. The only thing different in the new Pentium 4 3.0GHz compared to the predecessor is the multiplier. Pentium 4 3.06 uses 23x multiplier, while the newcomer – 15x.

That is why the only thing Intel had to do to implement 800MHz bus support in the new CPUs was to make sure that they are supported by the chipsets and mainboards available in the market. This is exactly the reason why very soon we will see new i875 (Canterwood) and i865 (Springdale) core logic sets, which will not only support faster bus but also allowing the use of adequate memory subsystem built of dual-channel DDR SDRAM.

For Intel the launching of the new i875 and i865 chipset families will mean successful getting past another point in Pentium 4 platforms and NetBurst architecture evolution. The first Pentium 4 processors featured 256KB L2 cache and 400MHz system bus. Later on, as the company shifted to 0.13micron technology the L2 cache size of Pentium 4 processors grew up to 512KB and the Quad Pumped Bus frequency – to 533MHz. the chipsets developed specifically for these processors have already acquired some innovations by then: they features support for USB 2.0 protocol and worked with DDR SDRAM, which was getting more and more popular. In the end of last year Intel added Hyper-Threading technology to the list of its features and updated its core logic sets having provided them with DDR333 SDRAM support.

The new chipsets, which will be used together with the Pentium 4 CPUs supporting faster bus, will boast a few innovations. Among them we could list the following:

• 800MHz system bus support;
• Dual-channel DDR400/DDR333/DDR266 SDRAM;
• PAT (Performance Acceleration Technology);
• Serial ATA protocol and RAID 0 and 1 arrays support;
• CSA (Communication Streaming Architecture) for Gigabit Ethernet;
• Intel Extreme Graphics 2 - updated integrated graphics core;
• AGP 8x.

Let’s dwell on these and some other features now.

800MHz System Bus Support. The higher 6.4GB/sec data transfer rate between the CPU and the chipset allows improving the processor performance due to the fact that it spends less time waiting for the new data. High data feed rate is very important for contemporary Pentium 4 CPUs with NetBurst architecture and Hyper-Threading technology.

Dual-Channel DDR400/DDR333/DDR266 SDRAM. High-speed processor bus requires faster memory subsystem. Therefore, new Intel chipsets will feature a dual-channel DDR SDRAM controller, like the one used in i7205 (Granite Bay) chipset. However, 800MHz processor bus will also require fast memory to be used in the system. In order to provide a data stream fast enough for the 800MHz processor bus, new chipsets will support dual-channel DDR400 SDRAM.

So, it is exactly the two DDR SDRAM channels used in the new platforms with 800MHz Quad Pumped Bus that make these systems well-balanced. No other memory types can cope with the increased processor bus bandwidth.

PAT (Performance Acceleration Technology). This technology is intended to improve the chipsets performance. It speeds up the system by taking advantage of the “internal reserves”. Namely, this technology reduces the latencies when the CPU works with the system memory via the chipset. You don’t need any specific memory modules to make this technology work: all the necessary optimization is made inside the chipset North Bridge and in the BIOS. When the CPU addresses the system memory, the chipset omits some operations typical of other core logic sets and performs certain operations faster.