During the announcement of the Radeon RX 6000 series graphics cards, AMD noted Smart Access Memory (SAM) technology, which provides an increase in performance when the accelerator is running in conjunction with Ryzen 5000 (Zen 3) processors. Previously it was reported that Ryzen 3000 and older AMD chips, unlike Intel processors, allegedly do not support SAM technology due to the lack of the necessary hardware and support for instructions PDEP… But it turned out that not everything is so simple.
To begin with, we recall that SAM is based on the Resizable BAR (Base Address Registers) resizing technology, which is part of the PCI Express interface specifications since version 2.0 and is not exclusive to AMD. Whereas in ordinary Windows-based PCs, processors can directly access only a portion of the graphics memory up to 256 MB, the Resizable BAR technology can expand the data channel, allowing the processor to use the entire video memory array at once. This removes potential bottlenecks and delivers up to 15% performance gains in select games. This is especially true now, when the amount of video memory used by games often exceeds even 10 GB. Resizable BAR works well on a combination of Radeon RX 6000 and Intel processors on ASUS and ASRock boards. Since this is part of the PCI Express specification, NVIDIA also plans to add support for this technology to some of its graphics accelerators.
Rumors regarding the lack of SAM support in the Ryzen 1000, 2000 and 3000 chips were initially denied by Ian Curtress of Anandtech, who received clarification from AMD itself. It turns out SAM does not rely on the PDEP instruction and will work no matter how well the instruction is supported by the processor.
MSI and ASUS have now demonstrated SAM performance on various AMD Ryzen processor series that do not have Zen 3 architecture. According to the screenshots posted, AMD Ryzen 4000G and Ryzen 3000 series processors with Zen 2 architecture will also support SAM on motherboards with AMD 500 series chipsets … ASUS has shown the possibility of using the Re-Size BAR with the Ryzen 7 1700 processor based on Zen.
Earlier this week, Igors’LAB posted a story that NVIDIA is also working on an alternative to AMD SAM technology. Discussions are allegedly underway within the company as to whether the GeForce RTX 30xx series should support this technology. It is not clear whether any final decisions were made on this matter, but given that NVIDIA said that it was considering adding support for Resizeble BAR, it would be too late to retreat.
Meanwhile, AMD has not made any public announcements regarding potential SAM support on older Radeon GPUs.
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