AMD Ryzen 3000 "Matisse" processors based on the "Zen 2" microarchitecture, as well as older AMD processors based on "Zen+" and "Zen" microarchitectures, do not support the company's Smart Access Memory (SAM) feature being introduced with Radeon RX 6000 series graphics cards. SAM is essentially a branding of the Resizable Base-Address Register (Resizable-BAR) feature developed by the PCI-SIG; which enables a processor to see a graphics card's entire video memory as a single addressable block, rather than through 256-megabyte apertures. Apparently the PCI-Express root complex of Ryzen 5000 "Vermeer" processors introduce a PCIe physical-layer feature called full-rate _pdep_u32/64, which is required for resizable-BAR to work.

It gets more interesting—Intel processors have been supporting this feature since the company's 4th Gen Core "Haswell," which introduced it with its 20-lane PCI-Express gen 3.0 root-complex. This means that every Intel processor dating back to 2014 can technically support Resizable-BAR, and it's just a matter of motherboard vendors releasing UEFI firmware updates for their products (i.e. Intel 8-series chipsets and later). AMD extensively advertises SAM as adding a 1-2% performance boost to Radeon RX 6800 series graphics cards. Since this is a PCI-SIG feature, NVIDIA plans to add support for it on some of its GPUs, too. Meanwhile, in addition to AMD 500-series chipsets, even certain Intel 400-series chipset motherboards started receiving Resizable BAR support through firmware updates.