Recently AMD implemented a new Smart Access Memory (AMD SAM) technology for its Radeon RX 6000 GPUs and Ryzen 5000 series of processors. But this is not an entirely new technology, since it is based on the Resizable BAR open standard included by PCI-SIG in the PCIe 3.0 standard in 2008.
Resizable BAR is a tech via which assets can be requested as-needed and accessed. As such, the CPU will efficiently access the entire frame buffer. Moreover, transfers can occur concurrently, rather than queuing, whenever there are multiple requests.
AMD has already showcased this tech in action, showing an 8-15% performance boost in some games. This is free performance boost, without any image degradation/loss.
With the release of the RTX 3060 12GB Ampere GPU, Nvidia has also confirmed initial support for “Resizable BAR” feature which is going to be compatible with the company’s GeForce RTX 3060 desktop graphics cards and GeForce RTX 30-series laptops.
Resizable BAR is an optional PCI Express interface technology. As you move through a world in a game, GPU memory (VRAM) constantly transfers textures, shaders and geometry via many small CPU to GPU transfers. With the ever-growing size of modern game assets, this results in a lot of transfers. Using Resizable BAR, assets can instead be requested as-needed and sent in full, so the CPU can efficiently access the entire frame buffer.
And if multiple requests are made, transfers can occur concurrently, rather than queuing.
GeForce RTX 30 series laptops with Resizable BAR-capable Intel and AMD CPUs are now available to purchase. You need to check with each laptop manufacturer to confirm whether Resizable BAR is supported on that particular model.
For desktops, you will need a compatible CPU, compatible motherboard, motherboard SBIOS update, GPU VBIOS update (the GeForce RTX 3060 already ships with the necessary BIOS) and new GeForce Game Ready driver to enable Resizable BAR.
According to Nvidia’s press release statement, as of February 25th, 2021, the following CPU chipsets and CPUs support Resizable BAR on GeForce RTX 30 series desktop GPUs.
“Intel has been working with NVIDIA to enable Resizable BAR, an advanced PCI-Express technology, across the PC ecosystem,” said Fredrik Hamberger, GM of Premium & Enthusiast Laptop Segments at Intel.
“This feature can give gamers an extra boost in gameplay FPS on Intel’s new 11th generation H/S and select 10th generation systems when paired with supported graphics cards, including NVIDIA GeForce RTX 30 Series GPUs.”
At the same time, NVIDIA is also working with motherboard manufacturers around the world to bring Resizable BAR support to compatible products. As of February 25th, 2021, the following manufacturers are offering SBIOS updates for select motherboards to enable Resizable BAR with GeForce RTX 30 Series desktop graphics cards.
For enabling the Resizable BAR feature on any GeForce RTX 30 series GPU, after having updated your motherboard’s firmware/BIOS, you’ll need to update your GPU, and download the latest Nvidia game ready driver.
The GeForce RTX 3060 desktop graphics cards launched on February 25th, 2021, come with a pre-installed Resizable BAR-ready VBIOS. If you purchase one, all you need is a compatible motherboard and motherboard SBIOS, and the latest game ready driver.
Later on in March 2021, NVIDIA will release downloadable VBIOS updates for all Founders Edition GeForce RTX 30 series GPUs to enable Resizable BAR, and likewise, partners will release VBIOS updates for their custom models, too.
In practice, the performance benefits of Resizable BAR can vary substantially from game to game. According to NVIDIA’s testing, some titles benefit from a few percent, up to 10%. However, there are also titles that see a decrease in performance, so NVIDIA will be pre-testing titles and using game profiles to enable Resizable BAR only in games where it has a positive performance impact.
That way you won’t have to worry about bugs or performance decreases, and won’t have to rely on the community to benchmark each title and discover whether Resizable BAR is beneficial in the games you’re playing.
With the release of the newest GeForce game ready driver, Nvidia has enabled initial Resizable BAR support on GeForce RTX 3060 graphics cards and in the following titles, as of February 25th, 2021:
- Assassin’s Creed Valhalla
- Battlefield V
- Borderlands 3
- Forza Horizon 4
- Gears 5
- Metro Exodus
- Red Dead Redemption 2
- Watch Dogs: Legion
Lastly, in order to verify whether the new Resizable BAR feature is working properly, on the bottom left of the NVIDIA Control Panel, simply click “System Information”, and in the new window look for “Resizable BAR” on the right. If it says “Yes”, then you’re set.
It remains to be seen when Nvidia will enable Resizable BAR support on its entire Ampere lineup of GPUs, or even offer support for previous gen Turing and Pascal GPU architecture lineup.
Stay tuned for more tech news!