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
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.