How will AMD's chipsets change in the future?



Chipsets mounted on motherboards play a role of assisting the CPU, but in recent years, other parts have taken on that role and are becoming more and more eliminated. SkyJuice, who runs a technical blog focusing on the CPU socket 'AM5' developed by AMD, explains such a chipset.

Site Launch Exclusive: All the Juicy Details on AMD's Quirky Chipset Solutions for AM5!

https://angstronomics.substack.com/p/site-launch-exclusive-all-the-juicy

A chipset is a companion device that sits on the motherboard of a computer, pairs with a main computing device such as a CPU, and acts as an input / output signal hub that mediates between devices and connectors on the motherboard. This chip 'bridges' the gap between input / output (I / O) and the processor, with the traditional ' Northbridge ' for high-speed I / O to system memory and graphics cards, and the ' Southbridge ' for storage. And processing slow I / O to the network. In this architecture, the CPU is designed specifically for computing and processing power, and one high-speed link to the northbridge is sufficient, so the chipset can focus on I / O distribution and management. I can do it.

However, as technology has advanced and system design integration has progressed, the role of these chipsets has diminished. The main processor already has basically all the I / O interfaces onboard, including memory, PCI Express, storage devices, USB, and even integrated graphics display output. For this reason, these SOCs completely eliminate individual chipsets.

In fact, AMD's Ryzen series desktop processors don't even need a 'chipset' to work, they just need a small activator (Knoll). Almost all desktop motherboards still include chipsets, even though these activators under the X300 and A300 brand names do not provide additional I / O.

However, modern chipsets act as I / O expansion hubs, not like multi-port USB dongles. Chipsets help one connect to more devices on the device, but all data must communicate over the equivalent bandwidth of a single port. Below the chipset-to-processor uplink bandwidth, the performance difference is negligibly small. 'It can be said that the chipset has become a beautified PCIe mux switch ,' Sky Juice said.



From the beginning, AMD's client desktop platform in the

DDR5 era was designed to rely entirely on chipsets designed and manufactured by third parties. This is unlike the previous generation high-end X570 chipset from 2019 on the AM4 platform, AMD repackaged and repackaged its client I / O die chipset for use as a 'beautified PCIe mux'. SkyJuice says that he is using it.

This chipset variant (Bixby) sleeps without unused features such as memory controllers and PHYs, resulting in high-cost, high-power chipset solutions that increase motherboard costs and selling prices. Especially. On the other hand, the first two years of AMD's first X570 board design required an active cooling fan to cool the chipset. All this was done to provide a chipset solution for PCIe Gen 4 link speeds that third-party manufacturers couldn't handle at the time.

Now that PCIe4 is ready, AM5 will return to a third-party-only solution, as was the original ASMedia chipset, X370, B350, A320, X470, B450 branded on the 2016 AM4 launch platform. It was decided.

For AM5, we also intended to dual source these chipsets from two third-party suppliers, ASMedia and MediaTek. However, according to recent trends, each company has been conducting verification using ASMedia's silicon, and it is unknown when MediaTek will supply the chipset.



The A-class low-end chipset configuration will be released at a later date at the timing when the lower Rembrandt APU will be released at AM5. The high-end X670 chipset has a unique configuration in which two independent ASMedia

PROM21 (Promontory 21) chipsets are connected in a daisy chain . The first chipset connects to the CPU and the second chipset connects to the first chipset.

This daisy-chain chipset solution can dramatically reduce design costs as ASMedia only designs one chipset, while AMD increases motherboard I / O extensions to multiple segments. It is said that it can be provided. If you have the constraint of designing only a single piece of silicon that spans multiple market segments, rather than designing a large, expensive die that meets top-end requirements and disabling the functionality of the mass market segment. SkyJuice analyzes that it is much more cost-effective to design for middle-end solutions in the mass market and double for the high-end.

Also, by placing two chipsets on the motherboard, there are two more essential bonuses. They do not have to be placed together in the same location, but rather it is advantageous to place the chipsets apart. That way, the first chipset acts as a signal repeater for the daisy-chained chipset, eliminating the need to add a signal retimer to send high-speed PCIe 4.0 signals to a location on the motherboard away from the processor. You can reduce the cost. Finally, splitting the high-end chipset disperses the heat source, reduces heat density, and allows passive cooling of the chipset, eliminating the need for fans that only increase cost and cause of failure.

However, it goes without saying that daisy-chained I / O systems increase bandwidth contention, system complexity, and potential failures, SkyJuice said. Daisy-chained solutions also carry an inherently high risk when trying to partition the hardware through virtualization, which can be a problem for I / O hubs with nested port assignments. It may work in the end, but it's certainly not the best way to connect a USB hub to another USB hub. The same is true for this chipset, where you can use the port directly from the processor.



AMD, which reintroduced the multi-chip processor with the original EPYC 7001 in 2017, is now trying to provide a multi-chip solution for seemingly safe things like chipsets. 'For AMD and ASMedia, we've taken this unique and quirky idea because of its apparent cost advantage,' SkyJuice said.

AMD announced the 'Ryzen 7000' at the keynote speech on May 23, 2022, revealing that the processor is equipped with a new 6nm I / O die. The new AMD Socket AM5 platform has a 1718-pin LGA design, supports up to 170W TDP processor, dual channel DDR5 memory, new SVI3 power infrastructure, and leads all-core performance with Ryzen 7000 series processors. AMD Socket AM5 also has the industry's most PCIe 5.0 lanes (up to 24 lanes), the fastest, largest, and most scalable desktop platform to support next-generation and higher-class storage and graphics cards. It is appealing by AMD that it is.

AMD Showcases Industry-Leading Gaming, Commercial, and Mainstream PC Technologies at COMPUTEX 2022 :: Advanced Micro Devices, Inc. (AMD)
https://ir.amd.com/news-events/press-releases/detail/1069/amdshowcases-industry-leading-gaming-commercial-and

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