Ryzen AGESA exposes more memory overclocking options

Over the past couple months, we've come to understand that memory speed and latency plays a major role in Ryzen CPU performance. Higher speeds and lower latencies are desirable for getting the most out of a Ryzen chip. Outside of a few motherboards with external base-clock generators, however, the memory multipliers for Ryzen CPUs have maxed out at 32. With a 100-MHz default base clock, that means builders have been limited to running overclocked RAM at DDR4-3200 speeds.

Today, that all changes. AMD has announced that its AMD Generic Encapsulated System Architecture, or AGESA, version will expose 26 new RAM tuning settings to tweakers looking to extract the most from their Ryzen systems' RAM. These updates should bring AM4 motherboards' firmware settings for memory tweaking more on par with that of the Intel competition.

Of the wealth of memory overclocking options AGESA will offer, the two most important settings to me are an extended range of memory multipliers (up to 40, or DDR4-4000) and the option to set command rates at one tick or two ticks (1T or 2T). For example, the hot G.Skill DDR4-3866 memory I have here requires a 38.66 multiplier and a 2T command rate, but those settings simply couldn't be dialed in on Ryzen motherboards under the current AGESA ( without resorting to changes in the base clock that also controls important bus rates like PCI Express. Changing that base clock rate could result in unexpected behavior, so it's a relief that the masses won't have to resort to that approach any longer. 

Of course, AMD is quick to point out that using memory speeds above DDR4-2667 or settings not in accordance with JEDEC values is considered overclocking. Overclocking RAM with these new knobs will void a Ryzen CPU's factory warranty, even if you're using the company's Ryzen Master utility. Still, the temptation of performance gains will probably be too much to resist for many Ryzen owners.

In news that will be music to the ears of another class of users, AMD also says that AGESA will improve support for PCI Express Access Control Services, or ACS. According to the company, these improvements will allow users who run virtual machines on their Ryzen systems to better manage the assignment of PCIe devices within IOMMU groups. In short, the company says this feature will let VM wizards dedicate multiple graphics cards within a Ryzen system to the operating systems of their choice, whether natively installed or virtual, among other benefits.

AMD says motherboard firmware incorporating AGESA will be available starting in "mid-to-late June." The company notes that some motherboard makers have already begun issuing beta firmwares for some products with the new AGESA on board, most notably Gigabyte with its AX370-Gaming 5 and Asus with its Crosshair VI Hero. Folks eager to push Ryzen memory performance to its limits will doubtless welcome this update warmly.


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