When AMD unveiled Bristol Ridge earlier in the month, they also released some details for their new AM4 platform. Used for Bristol Ridge and Zen, the new socket utilizes a new series of chipsets. So far B350 and A320 have been officially released for the mainstream and essential (budget) markets respectively. Now, we’re getting our first leak for the new enthusiast-oriented X370 chipset.
Known as the Promontory family, the new chipsets offer a reimagined take on what a chipset should do. As the top product, X370 offers the most connectivity as well the greatest flexibility. While B350 has overclocking, the X370 will reportedly feature additional support for 2x 16 PCIe Crossfire/SLI.
Starting with AM4, the CPU/APU apparently only outputs a total of 16 PCIe 3.0 lanes. For the B350 and A320, the chipset and standard ports like SATA and USB 3.0 take up 8 lanes, leaving 8 lanes for a PCIe 3.0 x8 connector. This cannot be split without a PLX chip, meaning B350 and A320 motherboards cannot support Crossfire or SLI which requires at least 2 sets of PCIe x4 lanes.
This is where X370 comes in which as we know from the leak will support Crossfire and SLI. Since the CPU/APU only supports a total of 16 PCIe 3.0 lanes, this means the X370 likely features some kind of splitter. I’m guessing the chipset will receive the regular 4 lanes + the 8 dedicated lanes but feature PLX functions to output 2x PCIe 3.0 x16 lanes. This will allow Crossfire and SLI to be supported.
Generally, PLX implementation cost the motherboard OEMs quite a bit but by bundling it into the enthusiast chipset, AMD will likely be able to reduce the cost. If our assumptions hold true, it will be interesting to see how well the implementation works given the slightly higher latency due to running the PCIe lanes through the chipset. It’s a tad disappointing that AMD isn’t giving more links out of the CPU.
At this point, the information we’re getting is still unconfirmed by AMD. For now, Bristol Ridge, AM4, and the corresponding chipsets are only released for OEMs. This means it’s going to be a rare motherboard that will use X370. Once AM4 hits retail with X30, we may finally find out what AMD has really done to their chips.
