How To Enable Resizable BAR In BIOS | Boost GPU Performance

To enable Resizable BAR in BIOS, disable CSM, enable UEFI mode, turn on Above 4G Decoding, and set Re-Size BAR Support to Enabled or Auto.

If your GeForce RTX 30 or 40 Series card isn’t reaching its full potential in modern games, a single BIOS setting is likely the culprit. Resizable BAR lets your CPU access the GPU’s entire video memory at once, replacing the older 256MB chunk limit. The result is a measurable frame rate uplift in titles like Cyberpunk 2077 and Assassin’s Creed Valhalla. Here’s exactly how to enable it on any compatible system without the guesswork.

What Is Resizable BAR and Why Enable It

Resizable BAR (Base Address Register) is a PCI Express feature that opens a wider data pipeline between the CPU and GPU. Without it, the CPU can only communicate with the GPU’s memory in small 256MB windows, which limits performance in scenes that demand frequent asset streaming. When enabled, the CPU can access the entire frame buffer at once. The result is free performance in well-optimized titles, often a 5-15% boost depending on the game and resolution.

NVIDIA, AMD, and Intel all support the feature, but it requires specific hardware, a current BIOS, and a few deliberate settings changes to activate.

Does Your Hardware Support Resizable BAR

Before you open the BIOS menu, confirm every component in your system is compatible. The feature won’t appear in the firmware if the hardware or software stack is incomplete.

How To Enable Resizable BAR In BIOS: The Steps That Work

The exact menu names vary slightly by motherboard brand, but the logical sequence never changes. Disable legacy compatibility, widen the memory aperture, then flip the Resizable BAR toggle.

The General Procedure (Every Motherboard)

1. Restart your PC and press DEL or F2 repeatedly during startup to enter the BIOS.
2. Navigate to the Boot tab and locate CSM (Compatibility Support Module). Set it to Disabled. If the option is hidden, your system is already in UEFI mode, which is required.
3. Go to Advanced and find PCI Configuration or PCIe Subsystem Settings.
4. Set Above 4G Decoding to Enabled. This widens the memory address space the CPU can use for the GPU.
5. In the same menu, set Re-Size BAR Support to Enabled or Auto.
6. Press F10 to save and exit.

Brand-Specific BIOS Paths

If the general steps don’t match your screen, use the exact path for your motherboard.

ASUS. Enter the BIOS using DEL. In EZ Mode, you’ll see a dedicated Resize BAR icon. Click it to set it to On, then press F10 to save.

Gigabyte. Enter the BIOS and switch to Advanced Mode (press F2 or F7). Go to Settings and enable Above 4G Decoding. Set Re-Size BAR Support to Auto. Then go to Boot and disable CSM Support.

ASRock. Go to Advanced then PCI Configuration. Enable Above 4G Decoding and Re-Size BAR Support. If those options are not visible, go to Boot and disable CSM first, then return to the PCI Configuration menu.

How To Check If Resizable BAR Is Actually Working

Enabling it in BIOS is only half the job. Confirm Windows is using the feature before calling it done.

• NVIDIA users: Open the NVIDIA Control Panel, click Help at the top, then System Information. Look for Resizable BAR on the right; it must say Yes.
• AMD users: Open AMD Radeon Software, go to Settings then Graphics. The Resizable BAR status will be visible there.
• Universal tool: Download GPU-Z and run it as Administrator. The Resizable BAR field in the bottom right will show Enabled when the feature is active.

Why Isn’t It Working? Common Problems Fixed

Roughly 90% of activation failures come from one of five simple missteps. Run through this list if you followed the steps above but the feature remains off.

The fix is almost always one of these. Start with the driver, then check the BIOS version, then confirm the boot drive is GPT if you plan to keep CSM disabled permanently.