Thursday, December 3rd 2020
AMD Radeon RX 6800 XT Tested on Z490 Platform With Resizable BAR (AMD's SAM) Enabled
AMD's recently-introduced SAM (Smart Access memory) feature enables users pairing an RX 6000 series graphics card with a Ryzen 5000 series CPU to take advantage of a long-lost PCIe feature in the form of its Resizable Bar. However, AMD currently only markets this technology for that particular component combination, even though the base technology isn't AMD's own, but is rather included in the PCIe specification. It's only a matter of time until NVIDIA enables the feature for its graphics cards, and there shouldn't be any technical problem on enabling it within Intel's platform as well. Now, we have results (coming from ASCII.jp) from an Intel Z490 motherboard (ASUS ROG Maximus XII EXTREME) with firmware 1002, from November 27th, paired with AMD's RX 6800 XT. And SAM does work independently of actual platform.
Paired with an Intel Core i9-10900K, AMD's RX 6800 XT shows performance increases across the board throughout the test games - which are games AMD themselves have confirmed SAM is working with. This means testing was done with Assassin's Creed Valhalla, Forza Horizon 4, Red Dead Redemption 2, and Rainbow Six Siege. The results speak for themselves (SAM results are the top ones in the charts). There are sometimes massive improvements in minimum framerates, considerable gains in average framerates, and almost no change in the maximum framerates reported for these games on this given system. Do note that the chart for Forza Horizon 4 has an error, and the tested resolution is actually 1440p, not 1080p.
Source:
ASCII.jp
Paired with an Intel Core i9-10900K, AMD's RX 6800 XT shows performance increases across the board throughout the test games - which are games AMD themselves have confirmed SAM is working with. This means testing was done with Assassin's Creed Valhalla, Forza Horizon 4, Red Dead Redemption 2, and Rainbow Six Siege. The results speak for themselves (SAM results are the top ones in the charts). There are sometimes massive improvements in minimum framerates, considerable gains in average framerates, and almost no change in the maximum framerates reported for these games on this given system. Do note that the chart for Forza Horizon 4 has an error, and the tested resolution is actually 1440p, not 1080p.
59 Comments on AMD Radeon RX 6800 XT Tested on Z490 Platform With Resizable BAR (AMD's SAM) Enabled
docs.microsoft.com/en-us/windows/win32/api/d3d12/ne-d3d12-d3d12_texture_layout
In that thread without further explanation and accompanied with the same questions as mine. From what I understand it might improve things above 4GB, but having fast access to 4GB chunks would still be a huge increase to the standard 256MB.
In the case of RDR2 might even be clip plane view distance matter I ponder too much loading quickly in instance at once at high details and not enough culling and detail reduction of the distance resources of textures and animations relative to the system hardware. There is a lot open world games that have problems trying to load way to much stuff at once in the distance that cause hitching and slowdowns if you don't tame those settings a bit. It's a good looking game and that kind of thing can kill performance quickly especially if VRAM or other system resources is a bit borderline.
What happens when you reduce memory frequency with the same latency to the FPS I ponder. If memory frequency impacts heavily the game defiantly is memory bandwidth limited to a degree. Still that doesn't explain how SAM is yielding such enormous FSP minimum gains to me that implies a bottle neck from storage or the PCIE interface itself. It could very well be the PCIE BAR size is the actual bottleneck in this instance. Really w/o increasing the BAR size there are still ways around the problem, but not necessarily as easy or simple at the same time.