NVIDIA has announced that all GeForce RTX 30 series graphics cards, desktop and laptop, will support Resizable BAR by the end of March. In-game performance benefits will vary, but NVIDIA claims it will be up to 10% in some cases. Independent benchmarks suggest that AMD has the lead over NVIDIA currently with its Smart Access Memory, though.
https://www.notebookcheck.net/NVIDIA-to-bring-Resizable-BAR-support-to-all-RTX-30-Founders-Edition-cards-by-late-March-AIBs-will-issue-VBIOS-updates-too-but-initial-performance-benefits-will-be-minimal.525794.0.html
This is all just marketing garbage to sell more and lockout all the people who don't have or can't get Ampere cards. 10% is like 10fps at the most on same settings in those 10 or so games, kinda pointless and should be free to all compatible hardware meaning all the way back to Pascal but ngreedia/LowIntel gangsters say otherwise. For instance all those of us who have 10th gen LowIntel cpus BUT have 20 series gpus are locked out because ngreedia gangsters. You can get 5%+ by a simple msiab lite OC of core and ram, debloated lite win10 add 10% more, dual channel ram add 10% etc