The Resizable Bar (or AMD Smart Access Memory) feature is a must for modern video cards and systems. It provides direct access to the video card memory and allows the processor to work faster with large amounts of data. Depending on the application, this can provide speedups ranging from 5% to 24%. The feature is certainly useful, but not available on older PCs. At the same time, technically it is part of the PCI Express 2.0 specifications, and in theory it can be activated on older motherboards.
Now this is possible thanks to a special modification from xCuri0. The developer has posted a patch for older boards that checks the UEFI firmware for compatibility and modifies it by activating the Resizable Bar. This method works even on old motherboards from 2011 for Intel Sandy Bridge processors.
But we must take into account that Resizable Bar requires a compatible video card to work. In Nvidia’s case, this is the GeForce RTX 30 series or later. Also, this does not provide acceleration everywhere; sometimes there is a drop in performance. Therefore, AMD and Nvidia use special profiles that use Resizable Bar and SAM only for specific games.
Source:
Tom’s Hardware