NVflash: how to flash a GPU BIOS (and get back to stock)

An interesting situation where I have in hand an EVGA XC3 Ultra gaming with Zotac bios installed – this card was on my desk after the thermals become a little undesirable. I thought I’d put it on the test bench, and low and behold:

An EVGA XC3 3090 Ultra running a Zotac Bios?

Very odd. So, Here’s how I find the correct original bios and then flash the card back to stock. This guidance would come in handy for anyone needing to return their GPUs to stock bios or folks wanting to try different bios in their GPUs

Updated July 2026. I wrote this on a 3090 in 2022 and the process hasn’t changed - NVflash is still the tool, and the current build (5.867 at the time of this update, from TechPowerUp) covers everything from Pascal right through Ada and Blackwell, so 40 and 50 series included. I’ve added sections below on downloading the right file, the commands you’ll actually use, and the signed-BIOS rules that catch people out on newer cards. The original walkthrough follows as written.

Where to download NVflash (and which file you want)

Grab it from TechPowerUp’s NVflash download page - that’s the copy I use, and it’s kept current. The zip contains both nvflash.exe and nvflash64.exe. On any Windows machine you’ve bought this decade you want nvflash64 - it’s the 64-bit build, and it’s why you’ll see “nvflash64” in half the forum threads on this subject. Same tool, same arguments. There’s a Linux build on the same page if your rig runs HiveOS or similar and you’d rather not pull the card.

One thing worth saying: only download NVflash from TechPowerUp or NVIDIA’s partner channels. A BIOS-flashing tool from a random mirror is not a risk worth taking.

Back up your BIOS before anything else

Before you flash anything, save what’s on the card:

nvflash64 --save backup.rom

That’s your way home if the new BIOS misbehaves. GPU-Z can also export the current BIOS (the little arrow icon next to the BIOS version field) - I tend to do both, because a spare copy costs nothing and a bricked card costs a 3090.

The NVflash commands you’ll actually use

The readme lists dozens. In years of flashing mining cards I’ve needed about five:

Command	What it does
nvflash64 --list	Lists your GPUs and their index numbers
nvflash64 --save backup.rom	Saves the current BIOS to a file
nvflash64 --version bios.rom	Shows what a BIOS file is, before you flash it
nvflash64 -6 bios.rom	Flashes, overriding a PCI subsystem ID mismatch
nvflash64 --protectoff	Disables write protection (older cards only)

Run CMD as administrator or none of this works. With more than one card installed, add --index=N (the number from --list) so you flash the card you meant to.

Signed BIOS, and why some flashes just won’t take

Since Turing (the 20 series), every NVIDIA vBIOS is cryptographically signed and the card will only accept a signed image. In practice: flashing one vendor’s stock BIOS onto another vendor’s card with the same board design - what I’m doing below - works fine, with -6 handling the subsystem ID mismatch. Flashing a modified BIOS doesn’t. The days of hand-editing power tables and reflashing ended with the 10 series, which is probably for the best given what I’d have done to my cards otherwise.

On 40-series cards NVIDIA tightened things further with board ID checks; the community answer is a patched variant called NVFlashK. It exists and it works, but that’s a deliberate step outside the guardrails - not something I’ve needed, since every flash I do is stock-to-stock.

Board compatibility

Most reference boards are more or less exactly the same. They may have more or fewer fans and 3 power sockets, not two – so keep an eye out for that. Fortunately, Techpowerup provides a list of boards based on the same design so, when you look up an EVGA XC3 Ultra on their site, you’ll see results like this:

Boards based on the same design as an EVGA XC3 Ultra

Clearly, it makes sense to choose designs with the same number of fans and PCI-E power sockets, for example; via the GPU bios page, you can gather some basic information about display port numbers and power requirements, and so on. A bit of googling never hurts,

So, download the correct bios, and NVflash. Put NVflash in a directory on your C:\ drive, and put the bios in there for safekeeping. Running NVflash is as simple as opening CMD as administrator and changing the directory to wherever you unzipped NVflash.

NVflash is ready to go

It’s essential to know the number the GPU has been assigned. There’s only one GPU in this machine so I’m guessing it’ll be 0. Use the –list argument to find out like so:

–list command in NVflash – our GPU is indexed as device <0>

So, if you’re feeling confident, here’s how to flash new bios to a GPU using NVflash:

The -6 overrides any mismatch in the board’s identification on the board’s device ID

If you’re happy, press enter:

Ready to go: press “Y” and then “Y” again moments later and let it do its thing

Once you’ve acknowledged that you’re happy to override the PCI subsystem ID, off it goes:

NVflash flashing the new bios

After this is complete, the machine will require a restart.

Once restarted I head to device manager to make sure all is well. It can take a few moments at boot for the device to reappear under “Display adapters”.

All seems well!

Finally, open GPU-Z to see what it thinks of the board:

The correct EVGA Bios now installed on this XC3 3090

And that, very briefly, is how to flash different bios to your GPU. EVGA Precision X1 will now recognize the card and will execute any newer firmware updates should they be available. Happy hashing!

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A 2026 footnote: the mining rigs this card came out of are long gone, but the card isn’t - that same 3090 now runs local LLMs, where 24GB of VRAM buys you a lot of model. If you’re tuning a card for inference rather than hashing, you want software limits rather than a BIOS flash these days: my nvidia-smi guide covers power-capping properly, and the GPU comparison shows where a used 3090 sits in 2026.