Creating a Modified BIOS for a GTX 400 Series GPU

This short tutorial is based on my Gigabyte GTX470 (GV-N470OC-13I rev 1.0), it’s a reference card with a slightly higher GPU clock of 630 MHz. This type of BIOS modification is working on other reference GTX4xx cards like the GTX460/465/480 as well. A standard GTX470 has the max GPU voltage locked at 1.087 V, but there’s an easy way to unlock up to 1.212 V. Here are some steps on how to unlock the max voltage on a GTX4xx GPU.

Step 1: Saving the Original BIOS

Save your original BIOS using GPU-Z, and make copy for editing. The default file type is a .bin file.

Step 2: Editing the BIOS

Download, unpack, and run NiBiTor v5.9. Open the copy of the previously saved BIOS by going to File > Open BIOS… (remember that your BIOS is a .bin file).

Next, go to Tools > Fermi Voltage.

Here we have a window with voltages on each performance level, but most important is the first line, Limit. Default value for Limit is 1.0875 V, and the maximum selectable is 1.2125 V. All that needs to be done is to change default value to 1.2125 V.

This doesn’t mean that your card will run at this voltage all of the time, this is only changing the maximum that can be selected using software. At this point, your card will still use a maximum of 1.0875 V in full load 3D mode unless you change performance levels or Windows software like MSI Afterburner or nVidia Inspector to adjust voltage.

Step 3: Saving the Modified BIOS

After making changes, save your BIOS as a .rom file (yes, the file type needs changing from .bin to .rom).

You can change other things too, like lowering 2D voltages, but that’s not the topic of this tutorial. Personalizing your settings is always nice, and it can be fun when you know how to do it right. Before making profile changes, it’s best to try them in Windows where, in the worst case, the system will hang up or show the blue screen if the setting are unstable.

Step 4: Flashing the Modified BIOS

Moving forward, now it’s time to flash your card with the modified BIOS. First, never update a BIOS on an overclocked system unless you are 100% sure that it’s stable. It’s a good idea to load defaults before flashing, just in case.

Download nvflash 5.95.0.1 (which I used) or newer for flashing.

I flashed while in Windows, but you can always make a bootable disk that includes the modified BIOS and nvflash files.

Flashing in Windows

Run the Command Prompt…

…change the directory to the folder with the modified BIOS and nvflash files, then type the command: nvflash bios.rom -5 -6 (where “bios” is your modified bios name).

Flashing in DOS

Create a bootable disk (USB drive, CD, Floppy, etc.), then put the nvflash files, your modified BIOS file, and also a copy of your original BIOS on the bootable disk. Both BIOS files need to be .rom files, the original BIOS can just be opened and re-saved in NiBiTor to change its file type. Insert your disk and restart the PC, enter the BIOS, and change the boot order to boot from the disk with the GPU BIOS and flashing files. Save and exit.

Once you’ve booted using your disk, use the exact the same command as used above. After a successful flash restart the PC. If something goes wrong, then it’s good to have the original BIOS to flash back to before restarting, as nothing will happen until you restart the PC. This is why the original BIOS was added to the bootable disk in addition to the modified BIOS.

There are many programs to make bootable pendrives or other disks. HP USB Stick Formatting Tool can be used, which it may not be the best, but it works.

Step 5: Did it Work?

System should boot as normal and depending on the changes made, it’s possible that system will detect a new graphics card.

Now it’s time to check if the BIOS changes are working. It’s best to use MSI Afterburner or nVidia Inspector.

Afterburner is much more popular, and I don’t think anyone will have problems finding the voltage settings. If the voltage slider is locked, then just click on the Settings button and check “Unlock voltage control” (other settings are optional).

Personally, I like nVidia Inspector. It’s really easy to use and includes more information on one small screen, but it doesn’t have monitoring. Below, you can see the unlocked slider up to 1.212 V.

Step 6: Optional Physical Modification (GTX470)

Even though you can set a higher GPU voltage now, there is limit to about 1.125 V. Most cards have protection (OCP/OVP) that doesn’t allow sustaining higher voltage for long periods of time. Sometimes that can be removed for even further overclocking. The modification is simple and all you have to do is short a resistor like on photo below.

More hardware modifications are well described on vr-zone.com, but most are only viable when using extreme cooling like dry ice, phase change, or LN2.

Step 7: Overclock with the New Found Voltage

Time for some results. How high could I push my card after these simple mods ?

My water cooled Gigabyte GV-N470OC-13I  was able to run quite stable at about 900 MHz core and passed the most popular benchmarks at about 920 MHz.

Almost 6.2k in 3DMark11 @ 920 MHz core
Over 23k in 3DMark Vantage @ 925 MHz core
Over 28k in 3DMark06 @ 925 MHz core

Of course, not all cards overclock the same, and there is no guarantee that your card will run at 900 MHz or more.

An Additional Use for BIOS Flashing

There are many reference GTX465 cards that can be unlocked to a full GTX470. All that is needed is reference GTX470 BIOS, that can be also modified using above tutorial. The only difference while flashing is use the command nvflash bios.rom -4 -5 -6 which is a forced flash that allows mismatched IDs between the BIOS and GPU being flashed. It’s not guaranteed that all GTX465 cards can be unlocked, but many of them can. For example, my friend is now the happy owner of TwinTech GTX465 that is working as a GTX470 with over 800 MHz core.

It’s also worth noting that on AMD’s side a reference HD6950 can be unlocked to a HD6970 with a BIOS flash as well.

Conclusion

This tutorial illustrates how simple it really is to edit and flash a graphics card BIOS. If you don’t want to try hard mods or you just don’t have good soldering skills, then it’s really worth it to spend half an hour or so to make your own unlocked BIOS. I also recommend using a good aftermarket air cooler or even water cooling while raising voltages because the core temperature under load will be much higher than when using the stock cooling solution.

– Woomack