The Intel Southbridge has also been given an overhaul, with one of the most important enhancements being the Direct Media Interface link to the Northbridge, which now supports a full 2.0 GB/sec. of system bandwidth. This component has long been a thorn in Intel's side, and the 266 MB/sec. bandwidth of the i875P and i865PE/G was so low, Intel stopped including a number on chipset diagrams. The current 9XX chipset generation solves that issue in a hurry, and brings the Intel chipset interface up to current standards.
The actual ICH6 Southbridge line has been upgraded as well, with the main enhancements falling into the areas of SATA, RAID and PCI Express. The ICH6 family includes the ICH6, ICH6R (RAID), ICH6W (Wireless LAN) and ICH6RW (RAID + Wireless LAN). One big change has been the forced transition to Serial ATA technology, and the ICH6R includes four SATA ports, while only having one PATA port. The ICH6 "R" variants also support RAID 0.1, and 0+1, with Matrix Storage Technology. The Matrix Technology controller allows hard drive hot-swapping, enhanced performance, and the flexibility of multiple volume support to enable both RAID 0 and RAID 1 volumes on a 2-drive array.
The ICH6 Southbridge also offers standard PCI Express support for peripheral cards, while maintaining current PCI support for up to 6 slots. The ICH6 line also features integrated LAN, Intel High Definition Audio, and USB 2.0 as standard. The ICH6 "W" variants include Intel Wireless Connect, which is a Southbridge option, and supports 802.11b/g (up to 54 Mbps) WLAN, along with WEP and WPA security. The High Definition Audio specifications have also been upgraded, and now feature 192 kHz, 24-bit 8-channel audio support, enhanced multi-streaming, and support for audio formats like THX and Dolby Digital Surround.
The LGA775 motherboards being evaluated are both from Intel and feature the 925X and 915G Express chipsets. The Intel D925XCV is the high-end Intel desktop model, and this 925X Express board has a full ATX design with all the performance features. It includes four DDR2 240-pin DIMM sockets, one PCI Express x16 slot, four PCI slots, and even 2 PCI Express x1 slots. The ICH6R Southbridge features 4 SATA connections (supporting RAID 0 and 1), a single PATA interface, 8xUSB 2.0, High Definition Audio, and Gigabit LAN.
The Intel D915GUX motherboard is a microATX design, and is not much larger than 9" by 9". This gives it a target market that is much different than the D925XCV, and the overall design, specifications and features are right in line with an integrated, mainstream 915G Express platform. It includes a full complement of four 240-pin DDR2 DIMM sockets, one PCI Express x16 slot, two PCI slots, and one PCI Express x1 slot. The D915GUX also supports onboard graphics through the GMA 900 core, and the ICH6RW (on our tested board - ICH6 is standard) includes 4 SATA connections (supporting RAID 0 and 1), a single PATA interface, 8xUSB 2.0, High Definition Audio, Gigabit LAN, and support for optional Intel Wireless Connect.
The LGA775 chipsets also bring with them a change to the power supply requirements. These Intel motherboards use a 24-pin PSU connector (like those for XEON servers), rather than the standard 20-pin version and will either require a new PSU, or a 20-pin to 24-pin adapter cable, assuming your current PSU is powerful enough.