First of all I would like to say that Intel will very soon introduce one more high-performance core logic set besides the today’s i925X Express. It will be Intel 925XE Express. Unlike the currently available solution, the XE version will also support 1066MHz processor bus. The corresponding CPUs supporting this bus should also be announced in Q3 2004.
Also I would like to say a few words about different South Bridge modifications, which can go with the new chipsets. Besides the ICH6 with pretty standard features listed in the table above, Intel is also planning to ship ICH6R South Bridge supporting Intel Matrix Storage Technology (i.e. SerialATA RAID), ICH6W supporting Intel Wireless Connect Technology (WiFi) and ICH6RW featuring both: WiFi and Serial ATA RAID.
The new i925 and i915 chipsets are not compatible with Intel’s older North Bridges. The thing is that Intel has finally given up the Hub Link bus with pretty low bandwidth of 266MB/sec to connect the chipset Bridges. Instead of this bus they now use a new DMI (Direct Media Interface) for the i925/i915 chipset families. Its bandwidth equals 2GB/sec (1GB in each direction). This bus is built similarly to PCI Express, and should provide sufficient bandwidth for all external devices connected to the chipset South Bridge, which you can actually see from the diagrams above.
As the bandwidth of the bus between the bridges got higher, Intel could avoid connecting the gigabit network controller directly to the chipset North Bridge now. That is why the CSA bus (Communication Streaming Architecture) bus used in the i875/i865 chipsets is no longer necessary, so the new i915/i925 solutions simply do not have it any more. Now all gigabit network controllers should better be connected to the South Bridge of the chipset via the PCI Express x1 bus.
Note that since all the new chipsets have been transferred to the PCI Express interface, Intel made it impossible to use the old AGP graphics cards in the new platforms. The new sets of core logic do not support this bus at all now. However, a few mainboard manufacturers found a way to implement AGP on their products based on i915 chipset, although this solution involves the PCI bus, which limits the bandwidth of such interface telling negatively on the graphics subsystem performance, of course. At the same time, i915 still supports DDR SDRAM side by side with the new DDR2 SDRAM. While the high-performance i925X Express cannot boast DDR SDRAM support.
I would also like to point out that the new Intel chipsets are not claimed to support the 400MHz Quad Pumped Bus. It means that you will not be able to use the old Celeron CPUs on Northwood-128 core in any of the new i915/i925 based mainboards. By the way, Intel 925X Express targeted for the fastest CPUs doesn’t support 533MHz bus. One more curious fact about the budget Celeron D (Prescott-256 based) processors support implies that the new mainboards based on i915 solutions will allow using this processor only with the regular DDR SDRAM, because DDR2 SDRAM is supported only together with the 800MHz Quad Pumped Bus.
Besides the support of DDR2 SDRAM, PCI Express x16 for graphics cards and PCI Express x1 for external devices, I would also like to draw your attention to the IDE controller, which has been changed greatly. Unlike the previous chipsets, the new ICH6 South Bridges support 4 Serial ATA-150 channels instead of 2. At the same time, the number of Parallel ATA-100 channels has been reduced to 1.
Although our today’s review is not going to focus on the details of the new generation integrated graphics core from Intel aka Intel Graphics Media Accelerator 900, which is used in the i915G and i915GV chipsets, it would be unfair if we didn’t mention it at all here. The thing is that this graphics core is dramatically different from all the graphics cores Intel would use in the previous generation products. Intel Graphics Media Accelerator 900 is compatible with DirectX9 and provides hardware acceleration of the pixel shaders version 2.0 and vertex shaders. Moreover, Intel Graphics Media Accelerator 900 works at 333MHz frequency, features 4 pixel pipelines and has the opportunity to allocate up to 224MB RAM for the Video subsystem. Such drastic changes of the features give us some hope that the new integrated chipsets from Intel will look pretty fine even against the background of such serious competitor as ATI RADEON 9100 PRO IGP. In particular, the performance of Intel Graphics Media Accelerator 900 could very nicely be illustrated with the score obtained in 3DMark 2001 SE test package run on a system with Pentium 4 3.0E CPU. We managed to achieve 5600 points. And according to 3DMark03, Intel Graphics Media Accelerator 900 outperforms all low-cost discrete graphics cards, namely NVIDIA GeForce FX 5200 and ATI RADEON 9200.
Having said a few good words about the new chipset families, we suggest going a bit more into details about them. Now we are going to continue our discussion of the major innovations introduced in the new i925/i915 chipsets.