How to Flash an NVIDIA GPU BIOS with NVFlash: Full Guide

NVFlash (nvflash64) is NVIDIA's command-line utility for reading and writing the BIOS (vBIOS) of a graphics card. Miners and enthusiasts use it to flash a modified BIOS in order to lower power draw, raise memory hashrate, unlock a higher power limit, or apply memory timings tuned for a specific algorithm.

This guide covers the full workflow — backup, compatibility checks, flashing and recovery — but the exact options can vary between NVFlash builds and GPU models.

If your goal is to reduce power draw or set a power limit, read the MSI Afterburner guide first: in most cases you do not need to flash anything.

⚠️ Read this first. Flashing the BIOS may affect your warranty and, if done incorrectly, can leave the card with a black screen. A power interruption or manual restart during the write process can corrupt the BIOS. Always make a backup before flashing and use a stable power source. Proceed at your own risk.

What NVFlash cannot do: signed BIOS

Starting with the GTX 900 series (Maxwell, 2014), NVIDIA digitally signs its vBIOS, and NVFlash verifies that signature before writing. In practice this means you cannot flash a modified BIOS with custom memory timings, voltages or power limits onto a modern NVIDIA card. The tool will only accept an image signed by NVIDIA — that is, an official BIOS from one of the board partners.

If you are coming from AMD, where editing the BIOS with MorePowerTool or Polaris BIOS Editor is routine, that route is closed on NVIDIA. Any "modded" RTX BIOS you find online will either fail the signature check or is simply an official BIOS from a different vendor.

What NVFlash is actually used for:

• Restoring the stock BIOS from a backup after a failed experiment, or after buying a used card with an unknown firmware.
• Cross-flashing — writing another vendor's official BIOS onto a card with the same PCB and the same GPU. This is sometimes done to get a higher power limit (for example, an image from a variant of the card with a stronger VRM). It only works when the Device ID, memory configuration and board layout match exactly; the -6 switch bypasses the Subvendor check, but not the signature and not the GPU check.
• Updating the BIOS to a newer official release when the manufacturer has issued one (for example, to add Resizable BAR support).
• Reading and comparing the BIOS across several cards in a rig.

For reducing power draw, overclocking memory or setting a power limit on NVIDIA, use software instead of flashing: MSI Afterburner or the miner's built-in options (--pl, --cclock, --mclock and equivalents). It is safer, reversible, and in most cases gives the same result.

What you need before you start

Before touching anything, gather these:

• NVFlash, downloaded from a trusted source — TechPowerUp is the standard one the community uses.
• The target vBIOS file (.rom) — only from a source you trust (e.g. the TechPowerUp vBIOS database), and only one that matches your exact card.
• GPU-Z, to read your card's current Device ID, Board ID (SubVendor ID), and BIOS version.
• A USB stick or cloud folder to store your backup BIOS off the machine.
• Ideally, a UPS (uninterruptible power supply) — a power surge or outage during the flash is the #1 cause of a dead card.

Version note: as of the last update of this article (September 6, 2026), the current version is NVFlash 5.867 for Windows, released February 25, 2025 (nvflash_5.867.zip). Check the current version and its checksum on the download page before running the tool.

💡 Which executable do I use? Depending on the archive, you may see nvflash.exe and/or nvflash64.exe. Use the executable included with your download; on 64-bit Windows, use the 64-bit build when one is provided. The examples below use nvflash64.exe.

Step 1 — Preparation

1. Download NVFlash and extract it to a simple folder, e.g. C:\nvflash.
2. Copy your target vBIOS into that same folder and rename it to something short like RTX.rom. Short names mean fewer typos — and a typo in a flash command is a real risk.
3. If your NVFlash build or its error message requires it, disable the display adapter for the target card in Device Manager before flashing. Otherwise, leave the adapter enabled. Re-enable it after rebooting.
4. Open Command Prompt as Administrator:
   • Press Windows + R, type cmd, then press Ctrl + Shift + Enter (this runs it as admin).
   • Or: Start menu → type cmd → right-click Command Prompt → Run as administrator.
5. Navigate to your folder by typing:

cd C:\nvflash

Step 2 — Back up the current BIOS

Do this every single time, before any flash. This backup is your only guaranteed way back if something goes wrong.

nvflash64.exe --save backup.rom

(The short form -b backup.rom does the same thing.)

Then copy backup.rom to a USB stick or the cloud. If your card bricks, this file is your ticket to a rollback — but only if it's stored somewhere off the machine you might not be able to boot.

💡 Save the backup with NVFlash itself rather than GPU-Z. GPU-Z sometimes doesn't capture the full UEFI portion of the BIOS on newer cards, which can make a restore fail.

Step 3 — Check compatibility (this prevents most bricks)

Open GPU-Z and note three values for your card, then compare them against the vBIOS you want to flash:

Rule of thumb: matching Device ID is non-negotiable. A mismatched Board ID may be handled by -6 on some builds, but only use it when you have verified the BIOS and board compatibility. A mismatched Device ID should stop you cold.

Step 4 — Remove write protection

Some cards and NVFlash builds require write protection to be disabled before flashing. If your build supports this option and reports that the BIOS is protected, run:

nvflash64.exe --protectoff

You can confirm the current state at any time with:

nvflash64.exe --getprotection

💡 The exact protection behavior depends on the card and NVFlash build. If the command only prints a banner or fails, follow the instructions for that build and try disabling the display adapter in Device Manager before retrying.

Step 5 — Flash the new BIOS

Now write the new vBIOS:

nvflash64.exe -6 RTX.rom

• The -6 flag is commonly used to bypass a board-partner or subsystem ID mismatch. It does not make a BIOS for a different GPU chip safe to flash. Use it only after checking compatibility.
• NVFlash should show a summary of the current and target BIOS. Read every value carefully and confirm only when the target BIOS is intended for this exact card. The number of confirmation prompts depends on the build.

Let it finish. Do not touch the keyboard, do not restart, do not let the power cut out. This is the dangerous window.

Step 6 — Re-enable protection if supported, then reboot

If your NVFlash build supports re-enabling protection, do it after the flash reports success:

nvflash64.exe --protecton

Then:

1. Shut the computer down completely — ideally unplug it from the wall for ~30 seconds (a full cold boot, not just a restart).
2. Power back on.
3. Open GPU-Z and confirm the BIOS version has changed. If it has, the flash worked.

When these options are supported by your build, the workflow is: protectoff → flash (-6) → protecton → cold reboot.

Flashing a multi-GPU mining rig

With several cards, flash them one at a time, targeting each by its index. First list every GPU:

nvflash64.exe --list

This shows each card with an index number (0, 1, 2, …). Then run the unlock + flash for each index using the -i flag (e.g. -i0, -i1):

nvflash64.exe -i0 --protectoff
nvflash64.exe -i0 -6 RTX.rom

Then repeat for the next card:

nvflash64.exe -i1 --protectoff
nvflash64.exe -i1 -6 RTX.rom

It's slower because it's sequential, but doing them one by one — and respecting the indices — is what keeps errors down.

Recovery: if the card won't start

A card that won't POST after a flash may still be recoverable if the system continues to detect it on the PCIe bus. That detection is the key requirement.

Blind-flash / secondary-display method (the reliable one):

1. Get a working display source — either integrated graphics (iGPU) or a second working GPU.
2. Boot the PC with the display cable plugged into that working source, and the bricked card still installed but with no cable attached to it.
3. Windows will boot on the working display. Open an admin Command Prompt in C:\nvflash.
4. List devices to find the bricked card's index:

nvflash64.exe --list

5. Restore your backup to that card (replace 0 with its actual index):

nvflash64.exe -i0 --protectoff
nvflash64.exe -i0 -6 backup.rom

6. Fully power down (unplug ~30 seconds), then boot with the display back on the recovered card.

💡 Do not guess the index. Identify the target card from the --list output before running a write command; flashing the wrong card creates a second problem.

If the card isn't detected on the PCI bus at all (doesn't appear in --list), a software recovery usually isn't possible, and the fix moves to hardware territory (a dual-BIOS switch if the card has one, or a hardware programmer / service centre).

Useful commands (full reference)

Long forms and their short synonyms — use either one, not both. Prefix with -iX to target a specific card in a multi-GPU system.

Common errors and fixes

"BIOS Protected" / flash refuses to write Run nvflash64.exe --protectoff first. If that prints only the version banner and nothing else, disable the GPU driver in Device Manager, then retry.

"Detecting GPU failed" / "No NVIDIA display adapters found"

NVFlash cannot see any NVIDIA GPU. Check in this order:

1. Command Prompt is not running as administrator. Close it and reopen via "Run as administrator".
2. The card is disabled in Device Manager. If you disabled the adapter following instructions for a different NVFlash version, enable it again — some builds require the device to be active.
3. The driver is holding the device. Close the miner, MSI Afterburner, GPU-Z, HWiNFO and anything else that talks to the GPU. On Windows rigs, stopping the "NVIDIA Display Container LS" service before running NVFlash sometimes helps.
4. Wrong executable. On 64-bit Windows use nvflash64.exe; the 32-bit build may not detect the device.
5. The NVFlash build is too old or too new. Recent cards (RTX 40/50) need a current NVFlash release; older versions simply do not know their Device IDs. Download the latest build from TechPowerUp.
6. The card is not detected on the PCIe bus. If it is missing from Device Manager and GPU-Z as well, the problem is hardware: riser, power, slot. NVFlash cannot help here.

If all of the above is fine and --list is still empty, try the same command in Windows Safe Mode or on another system.

"PCI Subsystem ID mismatch" If the build supports it and the only mismatch is a verified board-partner/subsystem mismatch, -6 may allow the flash. It is not a substitute for checking the exact GPU and board compatibility.

"PCI Device ID mismatch" even with -6 This is a chip mismatch, and -6 will not override it. Your .rom is for a different GPU than yours — stop and get the correct vBIOS. Forcing an incompatible chip's BIOS will not boot.

The confirmation prompt does not accept your input Switch to an English keyboard layout and follow the exact prompt shown by your NVFlash build. Do not continue if you are unsure what the prompt is asking.

--protectoff does nothing on an RTX 30 Founders Edition (or similar)

A known quirk — disabling the driver in Device Manager usually clears it. Some AIB-specific BIOSes (e.g. certain EVGA variants) also need you to specify the device index explicitly with -i.

If a CUDA error appears after the miner starts, that is a separate memory, driver or DAG problem. See our CUDA out of memory guide.

FAQ

Can I flash a modified BIOS on an RTX card?

No. From the GTX 900 series onward, NVIDIA verifies the vBIOS digital signature, and NVFlash will refuse to write an altered image. Only official BIOS files can be flashed — your own stock one or a compatible one from another manufacturer of the same model. For power limits and overclocking, use Afterburner or the miner's parameters.

Is flashing a GPU BIOS safe? It carries real risk. Done correctly with a matching BIOS and a stable power source, it may be routine for a supported card — but a wrong BIOS, a power cut, or a manual restart mid-flash can brick the card. It may also affect the warranty. Always back up first.

Can I flash a laptop GPU with NVFlash? Often not possible with the standard desktop tool. Laptop OEMs may use additional firmware and hardware protections, so treat a laptop GPU as unsupported unless the laptop manufacturer and the exact NVFlash build explicitly support the procedure.

Do I still need to disable the GPU in Device Manager? It depends on the card and NVFlash build. Disable the adapter only when the build or the error message calls for it, and re-enable it after rebooting.

Does -6 let me flash any BIOS onto my card? No. -6 is used for some board-partner or subsystem ID mismatches. It does not override the GPU chip (Device ID), and it does not make cross-chip flashing safe.

Can NVFlash recover a bricked card? Sometimes — if the card is still detected on the PCI bus. Boot from a second GPU or iGPU with no cable on the affected card, then restore the backup using the correct index. See the recovery section above.

Where do I download NVFlash safely? From TechPowerUp. Avoid random re-uploads; a tampered flashing tool is a fast way to lose a card.

Conclusion

NVFlash is a tool for confident users, but the procedure itself is only a handful of commands: back up → protectoff → flash with -6 → protecton → cold reboot when those options are supported by your build. Check the Device ID above all, keep an off-machine backup, and remember that not every failed flash is recoverable.

The miner's golden rule stays the same: no backup, no flashing.

Content is provided for information only. Flashing a GPU BIOS is done at your own risk and may affect your warranty.