Answer:
Smart Access Memory is AMD’s alternative to Resizable BAR, delivering a better connection between the GPU and CPU for a solid performance bump.
While NVIDIA and Intel are slowly introducing Resizable BAR on their platforms too.
In late 2020, AMD announced their RX 6000 lineup of GPUs that are based on the RDNA 2 architecture. During the presentation, Lisa Su, the CEO of AMD, took a moment to focus on SAM or Smart Access Memory.
Su claimed that this new feature with the RDNA 2 graphics card would provide a performance boost of 5% to 15%, depending on the game. That’s a solid performance increase considering all you need to do is flip a switch.
What exactly does this feature do, and why hasn’t it been introduced earlier in the PC industry?
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How Does It Work?
In simple terms, when you enable Smart Access Memory, a stronger communication stream is created between the processor and the graphics card.
However, this new feature was initially developed only for the Ryzen 5000 generation of CPUs and RDNA 2 GPUs. This meant only the owners of the latest generations of hardware could utilize SAM. Otherwise, the feature was unavailable.
Fortunately, that is no longer the case. AMD has released motherboard BIOS updates, allowing SAM to work with Ryzen 3000 series CPUs. However, it is still limited to RDNA 2 (RX 6000) GPUs.
NVIDIA has had a say in this too, but we’ll look at their offerings later.
Performance Boost
The general idea of SAM is easy to understand, but where does the performance boost come from?
Without this new feature, the way CPUs and GPUs communicate is limited. Previously, the processor could only access a maximum of 256MB of the graphics card’s VRAM. For a long time, this was more than enough.
Today’s games are far more demanding, and most GPUs come with more than 6GB of VRAM. This made it logical to improve the processor’s access to the VRAM.
In other words, a stronger and more efficient connection between these two essential PC components was crucial.
By bypassing the bottlenecks, the Ryzen chip can now access more of the memory of RDNA 2 graphics cards.
Based on AMD’s claims, SAM can deliver a performance boost of around 10% in games such as Ashes of the Singularity: Escalation, Assassin’s Creed Valhalla, Forza Horizon 4, World of Warcraft: Shadowlands, and many others.
Tests have shown various results. Most recently, in a 2023 test by Games Choices in 10 different games, SAM does seem to have a significant effect on performance.
It’s Not A New Technology
Until recently, the public hadn’t heard of Smart Access Memory. It is something that was introduced in late 2020 by AMD.
Despite this, the technology is not new. The original name of this feature is “Resizable BAR,” and it has existed for quite some time. We are only beginning to see the true potential of this feature after it has been properly optimized.
Since AMD introduced the idea, both Intel and NVIDIA have been working to bring it to every platform and GPU.
At the start of 2021, NVIDIA officially released Resizable BAR support for 3060 GPUs and laptops with RTX 3000 series graphics cards.
To use this feature, the NVIDIA GPU needs to be paired with a Ryzen 5xxx, Ryzen 3xxx, Intel 10xxx, or Intel 11xxx.
This support could spread to older platforms over the next few years, but don’t get your hopes up.
Are Resizable BAR And SAM The Same Thing?
Is Smart Access Memory just a fancier name for Resizable BAR? Are they identical?
Well, they are similar, but there are also differences. AMD’s SAM feature is originally based on Resizable BAR, but it has been developed further to bring additional performance improvements.
As of writing this guide, enabling ReBAR on an RTX 3060 card won’t bring considerable performance improvements, as reported by reviewers and users.
Keep in mind that things could change with additional BIOS and driver updates.
Future Of Resizable BAR
AMD has merely revealed the outer layer of this fresh characteristic. We could observe SAM and Resizable BAR potentially delivering even more significant enhancements in the coming days. It remains uncertain whether new versions of SAM or ReBAR will be compatible with earlier systems.
Regardless, the field always embraces fresh characteristics and advancements.
