The Motherboard Continued
The nForce 4 SLI Intel Edition chipset is a 2 chip interface for Intel based motherboards. With AMD there is no need for a separate Northbridge, as there is no memory controller external to the CPU, this means all that needs to be on a Northbridge for AMD would be PCI Express ports, and this is easy to incorporate into a single chip. With Intel, the memory controller is external, meaning there is more circuitry, resulting in a 2 chip setup.
Like most other chipsets, the Northbridge contains the Netburst bus interconnect, DDR-2 memory controller and 20 PCI Express lanes. When SLI is enabled by the onboard paddle card, 16 PCI Express lanes are routed to the two slots with each getting a total of 8 lanes each. The remaining 4 are used for the two PCI Express x1 slots and any onboard devices that use PCI Express. Due to the amount of heat generated, Gigabyte recommends the use of the provided fan to best cool the Northbridge, especially when overclocking.
The Southbridge contains the Serial ATA controller, Parallel ATA controller, PCI Bus, Audio, USB and all the additional extras, including the Hardware Gigabit LAN, which nVidia is famous for. The Southbridge also puts out a bit of heat; this though only requires passive cooling.
Now we get to the first of the onboard devices, additional RAID. Gigabyte in the past has been a big fan of the ITE IDE controller chips; however, these don't include additional SATA ports. To this end, the Promise PCD20779 PCI SATA-II RAID controller is added. This controller has support for two SATA-II ports and a single Parallel ATA port. Like the nForce4 Southbridge, the Promise chip allows you to bridge RAID the IDE devices with the SATA devices connected to it. With two IDE and two SATA you can have a four drive RAID array using this setup.
Firewire is now a common place standard, used for DV Camera, External Storage enclosures and even Apple Ipod's, its good to see it added to this board. A two chip Texas Instruments PCI based Firewire controller is added, the larger chip is used to provide Firewire-400 support, while the smaller chip is used to give the controller Firewire-800 support.
Onboard there are two Marvell chips. The larger of the two chips is a PHY only chip designed to connect the nVidia Gigabit LAN to the RJ45 port. The smaller chip is a PCI Express based Yukon Gigabit LAN chip that gives the board its second Gigabit LAN port.