Intel Stakes Its Vision of the PC Future with 775 Launch

New Chipsets: 925X, 915G, 915P, 915GV, Continued

All the southbridge parts look the same. We picked the ICH6R.

There are four southbridge versions to choose from - of course at an extra cost only. The ICH6 is included with all 900 series Northbridge chips by default. ICH6R adds basic RAID functionality for $3 while ICH6W is the version with integrated wireless LAN controller for $5 more. ICH6RW finally offers everything with an extra $7 per chipset. We recommend that the ICH6 southbridge family be equipped with a heat sink, and in fact a heat sink is necessary because the component gets hotter than ever before. We even measured higher temperature numbers for the southbridge than for the Northbridge - at least the latter is cooled by the airflow originating from the CPU fan.

None of these new chipsets have much in common with their predecessors except for the now standard features, such as PCI slots, USB 2.0 ports, a basic sound system, controllers for storage devices etc. What's new are the four PCI Express x1 lanes, the Intel High Definition audio system and a fully featured four-channel AHCI Serial ATA controller.

Intel designed the 900 chipset family from scratch to have native PCI Express support. Hence it is no surprise to see that the proprietary interlink between MCH and ICH has been replaced by a PCI Express related circuit called DMI (Direct Media Interface). This uses four PCI Express lanes and delivers a bandwidth of 1 GB/s per direction. Because of this, it is no longer possible to use last-generation southbridge chips (ICH4 or ICH5) in conjunction with the latest Northbridges.

Chips And Packages

All the Northbridge chips come in a flip-chip ball grid array (FCBGA) with 1210 balls, while the southbridge is placed into a classic ball grid array with 609 connectors. Although the manufacturing process of Intel's chipsets has always been one generation behind the processor manufacturing, the chipsets have not been converted to 130 nm yet. Instead, all components are based on a 180 nm process, which would explain the high temperatures we noticed with the ICH6 chips.