Hardware explained
Resizable BAR (ReBAR): what it is and how to enable it
Reviewed July 2026
No magic promises, no invented numbers. Resizable BAR is a real, free, reversible setting that helps in some games and not in others. Here's what it does, who supports it, and how to enable it without breaking anything.
Step by step
01 What Resizable BAR (and SAM) is
The BAR (Base Address Register) is the window through which the CPU accesses the GPU's memory. Without Resizable BAR that window is just 256 MB, so the CPU reads VRAM in many small chunks. With Resizable BAR the window grows to cover the whole VRAM at once. Smart Access Memory (SAM) is AMD's marketing name for the same thing.
02 What it does in practice
It lets the CPU move textures and data to the GPU more directly, cutting back-and-forth transfers. In some games that eases a bottleneck and improves frames; in others the effect is none. It's a more efficient access path, not an overclock or extra hardware power.
03 Which GPUs and CPUs support it
GPU: NVIDIA RTX 30 series and newer, AMD Radeon RX 6000 and newer, and Intel Arc (which more or less requires it). CPU/board: most modern UEFI platforms support it; older systems may need a BIOS update. It needs pure UEFI boot — not Legacy/CSM.
04 Check your current state
On NVIDIA GPUs, the NVIDIA Control Panel shows “Resizable BAR: Yes/No” under System Information. On AMD you'll see it in Adrenalin. On Windows, Device Manager and third-party tools also report the BAR size. Confirm the state before changing anything.
05 Prerequisites: UEFI and an up-to-date BIOS
Resizable BAR requires UEFI boot mode with CSM disabled and, on many boards, a recent BIOS version. If your system boots in Legacy mode, you first need to migrate to UEFI (which may mean converting the disk to GPT). Update the BIOS from your board maker's official site before hunting for the option.
06 Enable it in the BIOS
Enter the BIOS/UEFI (usually Del or F2 at power-on). Look for “Re-Size BAR Support,” “Resizable BAR,” “Smart Access Memory” or “Above 4G Decoding.” Turn on Above 4G Decoding first, then Resizable BAR. Save and reboot. The exact names vary by motherboard vendor.
07 When it helps and when it doesn't
It helps most in higher-resolution, CPU-limited games and on Intel Arc GPUs. In many titles the difference is small or imperceptible, and in a few cases a game can perform the same or slightly worse. It's free and reversible, so it's worth testing — but don't expect a guaranteed jump everywhere.
08 If something goes wrong, it's reversible
If you see instability or no boot after enabling it, go back into the BIOS and turn Resizable BAR off (and Above 4G Decoding if needed). It's a firmware setting, not a physical change — you can always return to the previous state.
Support at a glance
A general guide — always confirm with your exact GPU and motherboard model. Some systems need a BIOS update before the option even appears.
| Component | Support / requirement |
|---|---|
| NVIDIA | RTX 30 series and newer |
| AMD | Radeon RX 6000 and newer (SAM) |
| Intel Arc | Supported; practically required for good performance |
| System | UEFI boot (no CSM) + a recent BIOS |
Where Neon helps
Enabling Resizable BAR is a BIOS change, so that part is on you — but Neon tells you whether it's even worth looking at.
- Detects your PC's Resizable BAR state and flags it honestly: enabled, available but off, or not supported by your hardware.
- Because it's a firmware setting, Neon won't flip it for you — it explains what it is, where to find it in the BIOS, and what to weigh before changing it.
- It automates the safe, reversible performance parts (power plan, startup apps, disk space) and leaves BIOS changes in your hands.
- It never invents a speed number. It tells you whether Resizable BAR is available, not a made-up “+X%” it couldn't measure up front.
Want the full picture of real wins? See the guide to speeding up your PC for gaming.
SourcesFuentes
- AMD Smart Access Memory (Resizable BAR) — AMD official SAM / ReBAR technology page