Smart Access Memory (SAM)
AMD's brand name for Resizable BAR — the feature that lets the CPU address all of the graphics card's memory (VRAM) at once instead of in small 256 MB windows. It can give a few percent extra performance in games, for free, if the platform supports it.
Problem: traditionally the CPU could only "see" 256 MB of VRAM at a time through a small PCIe window (BAR), which required many small transfers. Resizable BAR (a PCIe feature) opens all of VRAM for direct access → more efficient CPU→GPU data transfer. AMD marketed it as "Smart Access Memory" at the launch of Ryzen 5000 + Radeon 6000; Nvidia and Intel support the same underlying feature (Resizable BAR). The gain varies per game (a few percent, sometimes negative). It requires UEFI support and being enabled in the BIOS. A good example of a standard feature that gained traction through smart marketing. Related to Resizable BAR and PCIe.