Motherboard-Based Interconnects
AMD and Intel have never been particularly chatty when it comes to detailing the interfaces they use to communicate between chipset components, or even been logic blocks within a northbridge/southbridge. We know the data rates at which those connections run, and we know that they're generally designed to be as bottleneck-free as possible. Sometimes we even know where a certain piece of logic came from, such as the Silicon Logic-based SATA controller AMD used in its SB600. But we're often kept in the dark as to the technology used in building the bridge between components. PCI Express 3.0 certainly presents itself as a very attractive solution, similar to the A-Link interface AMD employs.
The recent emergence of USB 3.0 and SATA 6Gb/s controllers on a number of third-party motherboards may provide a glimpse into this process. Because Intel's X58 chipset does not provide native support for either technology, companies like Gigabyte had to integrate discrete controllers onto their boards using available connectivity.
Gigabyte’s EX58-UD5 motherboard did not have USB 3.0 or SATA 6Gb/s. However, it did include a x4 PCI Express slot:
Gigabyte replaced the EX58-UD5 with the X58A-UD5, which has support for two USB 3.0 and two SATA 6Gb/s ports. Where did Gigabyte find the bandwidth to support the new technologies? By using one lane of PCI Express 2.0 connectivity for each controller, cutting back on available external connectivity while adding functionality to the board, overall.
Besides the addition of support for USB 3.0 and SATA 6Gb/s, the only other real difference between the two motherboards is that the newer offering had its x4 slot removed.
Will PCI Express 3.0, like the standards that preceded it, wind up serving as an enabler of future technologies and controllers that won't make it into the next generation of chipsets as integrated features? Almost certainly.