I845E And I845G In Detail
There are a total of three new i845 chipsets: 845E, 845G and 845GL. The latter represents a low-cost variation and won't be launched for another few days, so we'll only investigate the 845E and G models here.
The 845E is technically the same as the 845, but it also supports Pentium 4 processors with 533 MHz FSB. With the introduction of 'ICH4', Intel showed that it wasn't satisfied to simply extend the specification, but went further to integrate support for USB 2.0. Without this addition, the 845E would have been left with no advantages over rival products from SiS (645DX ) and VIA (P4X333 ), except for its brand name. This would not have made for a good start.
As for the 845G , we can attest to the fact that there are even more improvements. It also comes with the new 'ICH4' south bridge and thus with up to 6 USB 2.0 ports. However, the two most important new features are in the MCH (Intel's Northbridge chip), the 82845G. This north bridge chip is what's responsible for the 'G' in the name of the chipset. 'G' stands for 'graphics' and that's the first important difference between i845E and i845G. Intel included an integrated 3D-graphics controller, which may not be exactly at the level of NVIDIA's nForce or ATi's Radeon IGP340, but fast enough to at least outdo a GeForce 2 MX200 and certainly i815's 3D-solution. For those ones of you, who can only yawn about this feature, Intel was nice enough to add support for external 3D-graphics as well, so i845G motherboards will come with AGP slots and support of 4x AGP.
This is not all, however. Undoubtedly, the memory interface is the most important new feature of i845G. Its memory controller is made for DDR memory based on the PC1600, PC2100, but also ready for the PC2700 or DDR333 standard. The support of this high-end DDR-memory type allows i845G to boost the performance of Pentium 4 significantly and enables Intel's new chipset to compete with DDR333 solutions from VIA and SiS. Unfortunately, the validation of this faster interface has not been finished due to the late completion of the DDR333 standard by the JEDEC, making this option a common overclocking feature. The higher memory bandwidth provided by the fast PC2700 DDR-SDRAM will of course also benefit the integrated graphics solution of i845G, but this issue will only play a minor role, as integrated graphics are hardly ever found in high-performance systems.