Find out what AMD Smart Access Memory is all about, and how to turn it on for a FREE BOOST in performance!
Smart Access Memory : PCIe Resizable BAR for AMD!
Smart Access Memory is AMD’s marketing term for their implementation of the PCI Express Resizable BAR (Base Address Registers) capability.
What does that mean exactly?
CPUs are traditionally limited to a 256 MB I/O memory address region for the GPU frame buffer. This of it as an “data dump” for stuff like textures, shaders and geometry.
Since this “data dump” is limited to 256 MB, the CPU can only send texture, shader and geometry data as and when the GPU requires them.
This introduces some latency – delay from when the GPU requires the data, and the CPU send them.
Turning on Resizable BAR or Smart Access Memory greatly expands the size of that data dump, letting the CPU directly access the GPU’s entire frame buffer memory.
Instead of transferring data when requested by the GPU, the CPU processes and stores the data directly in the graphics memory.
Graphics assets can be transferred to graphics memory in full, instead of in pieces. In addition, multiple transfers can occur simultaneously, instead of being queued up.
While this AMD graphic above suggests that Smart Access Memory will widen the memory path (and thus memory bandwidth) between the CPU and GPU, that is not true.
Smart Access Memory / Resizable BAR will not increase memory bandwidth.
What it does is let the CPU directly access the entire GPU frame buffer memory, instead of using the usual 256 MB “dump”. That reduces latency because the graphics assets are now accessible by the GPU at all times.
AMD Smart Access Memory : Performance Gains
According to AMD, enabling Smart Access Memory will give you a small but free boost of 5% to 11% in gaming performance.
Here is a summary of the test results from our article, RX 6800 XT Smart Access Memory Performance Comparison!
You can expect up to 16% better performance in some games, but no effect in certain games. But overall, you get a free boost in performance. There is simply no reason not to enable Smart Access Memory.
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AMD Smart Access Memory : Requirements
Since Smart Access Memory is just an AMD implementation of PCI Express Resizable BAR. Therefore, it can be be implemented for all PCI Express 3.0 and PCI Express 4.0 graphics cards and motherboards.
However, AMD is currently limiting it to a small subset of components, having validated it only for their new Ryzen 5000 series CPUs, select Ryzen 3000 Series Processors and Radeon RX 6000 series graphics cards.
So this is what you currently require to enable AMD Smart Access Memory :
Hardware
- AMD 500 Series Motherboards
- AMD Ryzen 5000 Series Processors, or
AMD Ryzen 3000 Series Processors (except Ryzen 5 3400G and Ryzen 3 3200G) - AMD Radeon RX 6000 Series Graphics Cards
Software
- AMD Radeon Software Driver 20.11.2 or newer
- Latest Motherboard BIOS (AMD AGESA 1.1.0.0 or newer)
AMD currently recommends these X570 motherboards, because they have updated BIOS available :
- ASUS X570 Crosshair VIII Hero WIFI (US|UK|AU|SG|MY)
- ASRock X570 Taichi (US|UK|AU|SG|MY)
- GIGABYTE AORUS X570 Master (US|UK|AU|SG|MY)
- MSI X570 Godlike (US|UK|AU|SG|MY)
AMD Smart Access Memory : How To Enable It?
If you have all of those supported components above, and updated your motherboard BIOS, you need to manually enable Smart Access Memory.
Now, the method will vary from motherboard to motherboard, and it probably won’t even be called Smart Access Memory.
Instead, look for variations of Above 4G Decoding, or Resizing BAR, or Resizable BAR, or Re-Size BAR Support.
AMD Generic Method
AMD has provided these generic steps to enable Smart Access Memory :
- Enter the System BIOS by press <DEL> or <F12> during the system startup.
- Navigate to the Advanced Settings or Advanced menu.
- Enable “Above 4G Decoding” and “Re-Size BAR Support“.
- Save the changes and restart the computer.
Step-by-Step Method For ASUS Crosshair VIII Hero
In our guide, we are using the ASUS CROSSHAIR VIII Hero (AMD X570) motherboard, as an example :
- First you will need to turn off CSM (Compatibility Support Module), or make sure it’s disabled.Go to the Boot menu and look for a CSM / Compatibility Support Module option.
- Set CSM (Compatibility Support Module) to Disabled.
- Go to the Advanced menu and look for the PCI Subsystem. In other motherboards, look for PCIe / PCI Express configuration options.
- Enable Above 4G Decoding.
- This will give you access to the Re-Size BAR Support option. Set it to Auto.
- Now go to the Exit menu, and select Save Changes & Reset.
- It will ask you to confirm the changes. Just verify both, and click OK.
After the motherboard reboots, AMD Smart Access Memory (PCIe Resizable BAR) will be enabled for your Ryzen 5000 series CPU and Radeon RX 6000 series graphics card!
CSM Warning For GIGABYTE AORUS X570 Master
AMD currently recommends these X570 motherboards, because they have updated BIOS available :
- ASUS X570 Crosshair VIII Hero WIFI (US|UK|AU|SG|MY)
- ASRock X570 Taichi (US|UK|AU|SG|MY)
- GIGABYTE AORUS X570 Master (US|UK|AU|SG|MY)
- MSI X570 Godlike (US|UK|AU|SG|MY)
CSM is disabled by default for the ASUS, ASRock and MSI motherboards. However, it is enabled by default in the GIGABYTE AORUS X570 Master.
If you installed Windows without first turning CSM off, it will be configured as non-UEFI. It will NOT boot if you enable Resizable BAR Support (Smart Access Memory).
You will need to reinstall Windows with CSM support disabled.
Recommended Reading
- Smart Access Memory Now Enabled For Ryzen 3000 CPUs!
- AMD Radeon RX 6700 XT : What You Need To Know!
- 2021 Lenovo YOGA Laptop Models Revealed!
- 2021 HP OMEN 15 (Valkyrie) Gaming Laptop Preview!
- 500 Radeon RX 5700 Cards Destroyed In Fire!
- AMD Smart Access Memory (Resizable BAR) Guide
- NVIDIA To Introduce Resizable BAR In February 2021!
- Get 16 FREE Mercedes-AMG F1 Wallpapers From AMD!
- Quake 2 RTX Now Supports Vulkan Ray Tracing!
- Precision Boost Overdrive 2 : Adaptive Undervolting Comes To Ryzen!
- RX 6800 XT Smart Access Memory Performance Comparison!
- Cyberpunk 2077 : AMD Ray Tracing NOT Available At Launch!
- AMD RDNA 2 Architecture : Tech Highlights!
- AMD Radeon RX 6800 XT Review : RDNA 2 Rocks!
- AMD CDNA Architecture : Tech Highlights!
- AMD Instinct MI100 : 11.5 TFLOPS In A Single Card!
- NVIDIA RTX A6000 + Omniverse : Specs + Details!
- VMware vSphere 7 Now Supports AMD SEV-ES Encryption!
- Desktop Graphics Card Comparison Guide Rev. 37.3
- AMD Ryzen 9 5950X In-Depth Review : 16-Core Behemoth!
- AMD Ryzen 7 5800X In-Depth Review : 8-Core Powerhouse!
- AMD Ryzen 5 5600X In-Depth Review : A Leap Forward!
- AMD Ryzen 5000 CPUs : Malaysia Price List + FREE Game!
- AMD Infinity Cache Explained : L3 Cache Comes To The GPU!
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