Resizable BAR lets your CPU access the graphics card’s entire video memory at once instead of through a small window, and enabling it can give a modest frame-rate improvement in some games at no cost. To turn it on you generally need a supported graphics card, a supported CPU and motherboard, a current BIOS, and a UEFI boot setup with the Above 4G Decoding and Resizable BAR options enabled.
The gain is real but not uniform: some games improve noticeably, many change very little, and a few can run slightly worse. This guide explains the idea in plain terms, lists the requirements, walks through the enabling steps, and shows how to confirm it is active. Support lists and defaults change with each BIOS and driver release, so check your motherboard and graphics card vendor pages for the latest compatibility notes.
What Resizable BAR Does
BAR stands for Base Address Register, the range of memory addresses the CPU uses to talk to a device. Traditionally the CPU could reach only a small slice of the graphics card’s video memory at a time and had to shuffle data through that window. Resizable BAR removes that limit, so the CPU can address the whole memory pool and send data more efficiently.
AMD markets a closely related feature as Smart Access Memory. The underlying PCI Express capability is the same idea, though vendors may add their own driver rules, so features and names differ by brand.
Where the benefit shows up
Games that stream a lot of assets, or that are limited by CPU-to-GPU transfers, tend to gain the most. Many titles show little difference, and gains tend to be small to moderate. Treat claims of large boosts with caution and read current reviews for the games you play.
Where it can backfire
A small number of games have shown slightly lower performance with the feature on, which is why vendors keep per-game profiles and settings. If a game runs worse, you can turn the feature off or use the driver’s per-application controls where available.
Requirements Checklist
Graphics card
Recent graphics cards from AMD, NVIDIA, and Intel support it. Some earlier models need a firmware update from the card maker, so look at your card’s support page. Intel’s Arc cards are generally designed to expect it, and performance can suffer without it.
CPU and motherboard
Many CPUs from the last several generations support the feature, but older platforms vary. Motherboards typically need a BIOS update that adds the option. Check the CPU and board support pages for your exact models.
UEFI boot mode
The system should boot in UEFI mode with the Compatibility Support Module (CSM) disabled. This usually means the Windows drive uses the GPT partition style, not the older MBR style.
Operating system and drivers
Use a current version of Windows 10 or 11 and the latest graphics driver. Linux also supports it, though the setup depends on the kernel and driver version.
Support by Platform Tier
| Tier | Typical platform | What to expect | What to do |
|---|---|---|---|
| Budget | Older CPU and motherboard, entry graphics card | Support may be missing or need BIOS and firmware updates | Check vendor lists first, update BIOS carefully |
| Mid-range | Recent CPU and board, modern graphics card | Supported on most, sometimes off by default | Enable in BIOS, confirm in driver |
| Premium | Latest platform, high-end graphics card | Typically on by default | Verify it is active after a BIOS reset |
How to Enable It
Exact menu names differ between motherboard makers, so use the steps below as a guide and look up your board’s manual for details.
- Update your motherboard BIOS to the latest stable version from the maker’s site. Follow the instructions carefully and do not interrupt the process.
- Update the graphics card firmware if the maker lists an update for your model.
- Make sure Windows boots in UEFI mode on a GPT disk. If it is on MBR, convert it with the built-in conversion tool, after backing up your data.
- Enter the BIOS, disable CSM, and enable Above 4G Decoding.
- Enable Resizable BAR (sometimes labeled Re-Size BAR Support or Smart Access Memory).
- Save the settings, restart, and install the latest graphics driver.
How to Confirm It Is Working
Do not assume the BIOS setting alone is enough. Verify that the feature is active in software.
Driver control panels
The NVIDIA control panel or app lists the status under system information. AMD’s software shows whether Smart Access Memory is enabled. Intel’s graphics software reports it for Arc cards.
Third-party utilities
Free hardware information tools show a Resizable BAR field on the graphics card page. Look for an “Enabled” value there.
Windows system information
The System Information utility can show whether the system boots in UEFI mode and whether secure boot is on, which helps when troubleshooting the prerequisites.
Troubleshooting When the Option Is Missing or Shows Off
If you followed the steps and the status still reads “No”, work through the usual causes in order. Most failures come down to a boot-mode or firmware mismatch, not a faulty part.
The BIOS option does not appear
Some boards hide Resizable BAR until Above 4G Decoding is enabled and CSM is disabled. Enable those first, save, and re-enter the BIOS. If the entry is still missing, the board probably needs a newer BIOS, or the CPU is not on its support list.
The system will not boot after changing CSM
That usually means Windows is installed in legacy mode on an MBR disk. Re-enable CSM to get back in, back up your data, and convert the disk to GPT using Microsoft’s documented conversion tool before disabling CSM again.
The driver reports it as unsupported
Graphics cards that need a firmware update will not report support until it is applied. Check the card maker’s support page for a firmware tool, and read its instructions closely, since flashing the wrong file can cause problems.
It is enabled but nothing seems faster
That is normal for many games. Vendors maintain lists of titles where the feature helps, and the rest may behave the same either way. Do not expect a visible change in every game, and do not keep chasing it if everything is running smoothly.
Should You Bother?
If the feature is available and the steps are simple, enabling it is low-risk and may help. If getting it to work requires a risky BIOS update on an older machine, weigh the small likely gain against the effort. A BIOS update should be treated carefully: use a stable power source and the official file for your exact board.
Linux, Handhelds, and Special Cases
On Linux, the feature depends on kernel and driver support, and the BIOS settings are the same as on Windows. Some graphics vendors enable it automatically when the platform supports it, while others require a driver parameter, so check your distro’s documentation. Laptops usually expose fewer BIOS options, and the setting may be controlled by the manufacturer’s firmware. In that case, check the laptop maker’s support pages and driver notes for a statement on support, and do not expect a menu toggle.
Before You Start
- Back up important files before changing disk or BIOS settings.
- Check the CPU, board, and graphics card support lists.
- Note your current BIOS settings so you can revert if needed.
- Download BIOS and firmware files only from the official vendor.
- Have a way to confirm status afterward, such as the driver control panel.
Common Mistakes
- Enabling the BIOS option without disabling CSM, so the feature never turns on.
- Switching boot modes on an MBR drive without converting it, then failing to boot.
- Updating the BIOS from an unofficial source or while power is unstable.
- Assuming every game will gain frame rate and not checking for regressions.
- Forgetting that a BIOS reset or update can clear the setting.
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Frequently Asked Questions
Is Resizable BAR the same as Smart Access Memory?
They rely on the same PCI Express capability. AMD uses the Smart Access Memory name, while other vendors use Resizable BAR, and driver behavior may differ.
Will it increase my frame rate?
Possibly, and usually by a small amount. Some games gain more than others, and a few see little or even a slight drop. Check current reviews for the titles you play.
Can I turn it off if a game runs worse?
Yes. You can disable it in the BIOS, or use per-game controls in the driver when your vendor offers them. Compare frame times before and after.
Does it work on older systems?
Sometimes, with a BIOS update. Platform support varies widely, so look up your exact CPU, board, and graphics card on the vendor pages before planning around it.
