Without it, the processor reaches the graphics card’s memory through a small window, traditionally 256MB, so data moves in many small transfers. Resizable BAR lifts that limit so the CPU can access all of the card’s video memory at once. In games that move a lot of data to the GPU, that can mean higher frame rates.

It’s off on many PCs, because it needs support from the graphics card, the processor, the motherboard and the BIOS settings together. This guide shows how to check and turn it on. It’s one step in our process for tuning a gaming PC.

Who it matters most for

  • Intel Arc graphics cards: Intel says Resizable BAR must be enabled for optimal performance with Arc graphics. The cards still work without it, but if you have one, this is the most important setting in this guide.
  • AMD Radeon: AMD calls it Smart Access Memory. AMD says it can improve performance in select titles, and its driver turns it on automatically on compatible systems.
  • NVIDIA GeForce: supported from the RTX 30 Series onwards. NVIDIA’s announcement reported gains of up to 12% in supported games, and the driver only uses it in games where NVIDIA has found it helps. Early RTX 3060 Ti, 3070, 3080 and 3090 cards may need a graphics card firmware (VBIOS) update first, from NVIDIA or the card’s maker.

Step 1: Check whether it’s already on

  • NVIDIA: open the NVIDIA Control Panel, click System Information in the bottom-left corner, and find Resizable BAR in the list. It says Yes or No.
  • AMD: open AMD Software: Adrenalin Edition and look for Smart Access Memory in the performance or system tuning settings.
  • Intel Arc: Intel says to use the Intel Driver & Support Assistant, which reports whether Resizable BAR is enabled.

If it says yes, you’re done.

Step 2: Update the BIOS and the graphics driver

Many motherboards only gained the Resizable BAR option through a BIOS update. Download the latest BIOS for your exact board from the maker’s support page and follow its instructions. Then update your graphics driver.

Not sure which board you have? Check your PC specs first.

Step 3: Make sure Windows boots in UEFI mode

Resizable BAR needs CSM (Compatibility Support Module) turned off, so the PC has to boot in UEFI mode rather than legacy BIOS mode. AMD also warns that with CSM on, Radeon cards can lose access to motherboard features including Smart Access Memory.

To check before you change anything, press Windows + R, type msinfo32 and press Enter. Next to BIOS Mode:

  • UEFI: you can safely turn CSM off.
  • Legacy: Windows is installed on an MBR disk and won’t boot with CSM off. Microsoft’s MBR2GPT tool can convert the disk, but back up your files first, or ask someone experienced to help. Don’t turn CSM off until it’s converted.

Step 4: Turn it on in the BIOS

The names vary by board maker, but the settings are the same everywhere:

  1. Restart the PC and press the BIOS key (usually Delete or F2). Switch to advanced mode if the board opens in a simple view.
  2. Find Above 4G Decoding (often under PCI subsystem, advanced or chipset settings) and set it to Enabled.
  3. Find Re-Size BAR Support or Resizable BAR. It usually appears right next to Above 4G Decoding once that’s on. Set it to Enabled or Auto.
  4. In the boot section, set CSM to Disabled (only if Step 3 showed UEFI).
  5. Save and exit, usually with F10.

Some boards use a different name or combine the settings into one switch. Intel notes it may be labelled Smart Access Memory or Clever Access Memory. Your motherboard manual shows where it is.

Step 5: Check it worked

Back in Windows, repeat Step 1. NVIDIA’s System Information should now say Yes, AMD Software should show Smart Access Memory as on, and Intel Driver & Support Assistant should report Resizable BAR as enabled.

If it still says no, recheck all three BIOS settings, make sure the BIOS and driver are up to date, and on an early RTX 30 Series card, check whether your card needs the VBIOS update.

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