Marketed as Smart Access memory on launch and an AMD exclusive feature, Resizable BAR is a PCI Express feature that allows the system to utilize the entire GPU memory rather than in smaller chunks. This allows memory dependent applications, particularly games to benefit from the larger pool of memory accessible and remove the bottlenecks of accessing it piece by piece. This in turn results in performance improvements.
The caveat here is should you enable it or not, and the easy is answer is yes. If you have resizable BAR on your system, which is now present for both Intel and AMD, you should absolutely use it.
Still, here’s some comparison numbers. As of this review, the RX 6000 graphics cards are the only GPUs to have resizable BAR support but NVIDIA seemingly will include it on their upcoming cards as well as existing RTX 30 cards through a VBIOS update.
Shadow of the Tomb Raider
Rainbow Six Siege
In general, we’re seeing improvements across the boards in these games from resizable BAR. We did test with DOTA2 and CSGO which yielded mixed results. We’ll explore Resizable BAR on a dedicated article once we get our hands on more samples to test with.