Learn About Resizable BAR: Settings That Give You Extra Gaming Performance

Did you know that with the right BIOS settings , you can squeeze more performance out of your existing hardware? If you don’t know about Resizable BAR and how it boosts performance, chances are you’ve turned it off. Here’s how you can enable Resizable Bar and what to expect from the feature.

Table of Contents

• What is Resizable BAR?
• How does Resizable BAR work?
• AMD Smart Access Memory
• Hardware requirements for Resizable BAR
• Use GPU-Z to quickly check the Resizable BAR status
• What performance benefits can you see?
• How to enable Resizable BAR
  • Step 1: Enter BIOS
  • Step 2: Turn on Above 4G Decoding
  • Step 3: Enable Resizable BAR support
  • Step 4: Save and exit

What is Resizable BAR?

Resizable BAR (Base Address Register) is a feature that allows the CPU to access the entire graphics card memory or VRAM at once instead of in small, fixed 256MB chunks. This feature is part of the PCI Express standard and is intended to improve the efficiency of data transfer between the CPU and GPU, improving overall system performance for GPU- intensive games and applications .

How does Resizable BAR work?

Under normal circumstances, the CPU can only access a portion of the GPU's memory at a time due to the limitations of the traditional PCIe standard. With the Resizable Bar disabled, the default bandwidth is limited to 256MB at a time. This limited bandwidth can cause bottlenecks, especially in data-intensive tasks like gaming, video editing, and simulation.

Resizable BAR eliminates these limitations by allowing the CPU to access all of the VRAM in a single operation. This increases the speed of data transfer between the CPU and GPU, resulting in improved performance in supported games and applications.

AMD Smart Access Memory

AMD's implementation of Resizable BAR is called Smart Access Memory (SAM). Introduced with Ryzen 5000 series CPUs and Radeon RX 6000 series GPUs, SAM allows these components to communicate more efficiently, taking advantage of the full potential of the hardware. AMD claims up to a 16% improvement in gaming performance with SAM enabled, although actual gains may vary depending on the game and specific hardware configuration.

Hardware requirements for Resizable BAR

To use Resizable BAR, your system must meet certain hardware requirements:

1. CPU : AMD Ryzen 5000 series or higher, Intel 10th generation or higher.
2. GPU : NVIDIA RTX 30 series or AMD Radeon RX 6000 series or higher.
3. Motherboard : Must support Resizable BAR, usually requires a BIOS update . AMD motherboards that support SAM will start with 400 and 500 series motherboards (e.g. X570, B550, A520, X470, B450). While Intel will also start with 400 and 500 series motherboards (Z590, B560, Z490, H470, B460, H410). Newer generation motherboards will likely support Resizable BAR, especially gaming and high-end motherboards.

Be sure to check your motherboard manufacturer's website for BIOS updates that enable Resizable BAR support.

Use GPU-Z to quickly check the Resizable BAR status

Before enabling Resizable BAR, you can check its status using CPU-Z . GPU-Z is a popular utility for monitoring graphics card information. To check if Resizable BAR is enabled, download and install GPU-Z. Once installed, open GPU-Z and look for the "Resizable BAR" entry to see if it is enabled or disabled. This can save you some time by confirming whether your system supports the feature. If Resizable BAR is disabled, you can enable it through the BIOS.

What performance benefits can you see?

Enabling Resizable BAR can result in performance improvements in many games by reducing latency and accessing GPU memory beyond the 256MB limit at a time. For example, AMD claims performance gains of up to 16% in some games, although actual benefits can vary. Many users report performance gains in the 6-10% range, with some games seeing even higher improvements. It’s important to note that not all games will benefit equally, and some games may even experience slight performance drops. That’s why it’s important to test your games first to understand the true performance impact of Resizable BAR.

How to enable Resizable BAR

If your system has a CPU, GPU, and motherboard that support Resizable BAR, you can easily enable this setting in your BIOS. It only takes a few steps to enable Resizable BAR. Here's how:

Step 1: Enter BIOS

Restart your computer and enter BIOS by pressing the DEL or F12 key as it boots. Some motherboards may use different keys to enter BIOS. A quick search online should tell you which key to press for your particular motherboard.

Step 2: Turn on Above 4G Decoding

In your computer's BIOS, navigate to the PCIe settings menu and enable Above 4G Decoding . This setting enables a 64-bit address space for PCIe devices, allowing access to more than 4GB of memory space for each PCI Express device like a GPU.

Step 3: Enable Resizable BAR support

Now that you have enabled 64-bit addressing, navigate to Re-Size BAR and toggle it to on. This option may be listed under different names depending on your motherboard manufacturer. AMD may call it Smart Access Memory (SAM), while Nvidia uses Re-Size BAR or Resizable BAR.

Some motherboards may have the Above 4G Decoding and Resize BAR settings merged into one. If so, switching Re-Size BAR to on will also enable Above 4G Decoding.

Step 4: Save and exit

Make sure all changes are made to the current XMP/EXPO profile you are using before hitting save and exit. After rebooting, check GPU-Z to confirm Resizable BAR is enabled.

If your system fails to boot or crashes, you may need to disable CSM (Compatibility Support Module) and make sure your system drive uses GUID Partition Table (GPT) instead of the older MBR format.

While Resizable BAR may provide a free and relatively easy performance boost, it is not without potential drawbacks. Some games may not see any benefit, and some may even perform worse. Additionally, enabling the feature involves changing the BIOS, which carries a small risk of system instability if not done properly. Always make sure you have the latest BIOS and drivers, and proceed with caution.

Overall, if you want to get the most out of your gaming rig, enabling Resizable BAR is a tweak worth exploring. It promises better performance without breaking the bank, making it an appealing option for gamers and PC enthusiasts alike.