The 955X Express is Intel's high-end desktop chipset for the Pentium D and Pentium Extreme Edition dual-core processors. As with the 925X chipset before it, it incorporates Intel's somewhat mysterious 'Memory Pipeline Technology' - said to improve throughput between the dual-core CPU and the system memory - to separate it from the more 'mainstream' 945P/G chipset.

The 955X Express chipset uses only DDR II memory and can handle up to 8GB in 533MHz, 800MHz and 1066MHz speeds. ECC memory is supported for workstation applications, though the bulk of desktop motherboards built on the chipset will probably leave this feature out. PCIe x16 is the video connector of choice; Intel currently supports only a single x16 slot for one graphics card, but a second can apparently be added via a "bridge" and rumors are wild that 955X Express can currently support dual PCI Express connectors if desired and allowed, and may even end up hosting ATI's upcoming CrossFire dual PCI Express technology.

The 955X Express is partnered with the Intel ICH-7R Southbridge controller, giving it ample multimedia capabilities. The ICH-7R only incorporates a single ATA-100 IDE controller (as Intel is trying to phase out Parallel IDE in favour of SATA) but provides four SATA II ports, an integrated Gigabit network adaptor and eight USB 2.0 ports. The 'R' means RAID, and the ICH-7R also supports RAID modes 0, 1, 5 and 10. Native Command Queuing is not supported by the ICH-7R's SATA controller as it is in nVidia's Intel chipset however.

One notable improvement over current PCI Express chipsets is in the number of PCI Express lanes that the 955X Express supports when connected to the Intel ICH-7R Southbridge. In addition to the 16 lanes reserved for the videocard, an additional six lanes can be used for six PCI Express x1 connectors, one PCI Express x4 and two PCI Express x1, or other combinations. That's two more lanes of PCI Express than most other chipsets can boast, giving this new Intel chipset a boost for the future.

The Intel 955X Express and ICH-7R chipsets are connected by means of a 2GB/s Direct Media Interface link, just like the previous generation 925X/ICH-6R Northbridge/Southbridge combination.