Resizable BAR: What It Is and How to Enable It on a Motherboard

What Is Resizable BAR?

Resizable BAR, short for Base Address Register, is a feature that expands how much graphics memory your CPU can access at any one time. In older systems, the CPU could only see a small window of the GPU's memory and had to repeatedly request the same data, which added overhead. With Resizable BAR, the CPU can address the full capacity of the graphics card, reducing these round trips and potentially improving performance.

This capability is tied to the PCIe architecture, but it only works when the CPU, GPU, and motherboard BIOS all support it. On modern platforms, it is often enabled by default, but many custom builds still need a manual toggle. The setting is usually located in the BIOS under a menu related to PCIe or advanced configuration. If your board was released in the last few years, there is a good chance a firmware update has added it.

Why Resizable BAR Can Help

In many games and creative applications, the CPU and GPU need to exchange data constantly. When the CPU can only see a small portion of the video memory, it has to access the same data repeatedly, which can create a bottleneck. Resizable BAR allows the CPU to see the entire frame buffer, reducing overhead and sometimes delivering higher frame rates.

The effect is not universal. Some games show a measurable improvement, others show no change, and a few can even lose a small amount of performance. The best candidates are titles that are CPU-bound or that stream large textures and geometry. For most people, enabling Resizable BAR is a free step that costs little time and can only help, provided your hardware is compatible.

Compatibility and Requirements

Resizable BAR requires three components to work together: a CPU that supports it, a graphics card that supports it, and a motherboard with a BIOS that exposes the option. Most recent desktop processors from both major vendors include support, and virtually all current GPUs are compatible. The motherboard must have a firmware update that implements the feature, so the first step is always to update to the latest BIOS.

You can check compatibility by entering your BIOS and looking for the setting, usually labeled Resizable BAR or Re-Size BAR. Some boards also require you to enable Above 4G Decoding first. If you do not see the option, your CPU, GPU, or firmware may not support it. Intel's desktop chipset lineup spans from entry-level to enthusiast, and the specific chipset on your board does not usually dictate this feature, but the motherboard manufacturer's update policy does. For more on how firmware and settings interact, see our BIOS guide.

How to Enable Resizable BAR in BIOS

Enabling Resizable BAR is usually a short process, but the exact menu names vary by motherboard vendor. The general workflow is the same: update the firmware, enter the BIOS, find the option, turn it on, and reboot. Here is the typical sequence.

Before you start, download the latest BIOS for your exact motherboard model from the manufacturer's support page. If you are not comfortable with the update process, see the guide on BIOS flashback. Once the update is installed, restart your PC and press the key shown on the boot screen to enter setup.

• Update the motherboard BIOS to a version that includes Resizable BAR support.
• Restart and enter the BIOS setup screen (often Del or F2).
• Navigate to the PCIe or Advanced menu and look for Resizable BAR or Re-Size BAR. On many boards, you must also enable Above 4G Decoding.
• Enable the option and save your changes. The PC will reboot.
• After Windows loads, you can verify the feature is active using your graphics card's control panel or a system information utility.

Troubleshooting Common Issues

If you enable Resizable BAR and encounter boot failures, crashes, or display issues, the quickest fix is to disable it again. Some older games or drivers can have compatibility problems. You can also check whether your BIOS is the latest version, as some early implementations had bugs that were later fixed.

Another common issue is that the option is hidden because Above 4G Decoding is not turned on. On many boards, that setting must be enabled before Resizable BAR appears. If you still cannot find it after updating, your CPU or GPU may not support the feature. In that case, there is no hardware workaround; you simply do not have a compatible combination.

Should You Enable It?

For most users, enabling Resizable BAR is a low-risk tuning step. It is a standard feature on modern platforms, and prebuilt systems often have it turned on already. If you built your own PC, it is worth checking whether the option is present. The worst case is no change in performance, and you can always revert to the previous setting.

When selecting a motherboard, a clear BIOS layout and regular firmware updates make it easier to take advantage of features like Resizable BAR. If you are shopping for a board, look for one from a manufacturer known for providing consistent updates. Our guides can help you compare gaming motherboards and budget options based on your needs.

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Questions

What does Resizable BAR stand for?

It stands for Base Address Register. In this context, it is a BIOS feature that lets the CPU access the full video memory of a graphics card instead of small segments.

Do I need a new motherboard to use Resizable BAR?

Not necessarily. Many existing motherboards gained support through a BIOS update. You need a compatible CPU and GPU, and the latest firmware, but you may not have to change the board itself.

Why is Resizable BAR not in my BIOS?

Your CPU, GPU, or motherboard may not support it, or the BIOS may be outdated. Some boards also hide the option until you enable Above 4G Decoding. Check your manufacturer's support page for a newer firmware and look in the PCIe menu.

Does Resizable BAR improve all games?

No. The impact varies widely. Some games gain several percent, others show no difference, and a few may lose a small amount of performance. It is most likely to help in CPU-bound titles that stream large amounts of data.

Can I disable Resizable BAR after turning it on?

Yes. Enter the BIOS, find the same setting, turn it off, and reboot. The change is reversible at any time.