Overclocking, Fan speed editing by modifying GeForce 8 BIOSes

[Denis W. Veteran]

I like my XFX 8800 GT Alpha Dog card, but one thing has bugged me since getting it last December: the fan failed to kick in whenever the GPU was too hot. I posted a thread in Hardware Hangout after I emailed XFX support for an updated BIOS. That didn't do squat unfortunately; it also led to a few points lost in 3DMark2006. For the next few months I was forced to use RivaTuner to set temperature thresholds. No RivaTuner? Then no game. Nothing's worse than seeing artifacts raining down your screen while in, say, Crysis. :p

After reinstalling Vista x64, I realized that I'd have to put Vista into a permanent Test Mode to get RivaTuner to load. With the watermark "Test Mode" on my desktop, this wasn't going to work. Then I noticed in a review of the 8800 GT Alpha Dog they mentioned editing the BIOS with a tool called NiBiTor. Sure enough, there were settings to control the temperature thresholds used by my card to appropriately kick in the fan when needed. After rebooting with my modified BIOS, all is well. No more additional software needed. (Y)

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How to edit your card's BIOS:

NOTES:

1. As always, flashing any firmware to a hardware device is risky. Keep your PC adequately powered while flashing. And definitely DON'T skip the step of backing up your card's original BIOS.

2. This was tested on my 8800 GT. This may work for pre-8xxx cards - if so, post your results here. The tools listed in this guide will work on pre-8xxx cards, however your options for tweaking temperature settings may be different.

3. This was tested on Vista Business SP1 x64. It should work on all Windows NT-based OSes.

4. All required tools in this guide are provided in a ZIP file. Click here to download the package.

Step 1: Save your original BIOS to disk

Grab a spare USB key and format it with the HP USB disk storage format tool - HPUSBFW.exe. (Run as administrator for Vista.) Tick "Create a DOS startup disk," and point the folder to "DOS Files" located in the same folder as the tool. Now browse to your key in Explorer and copy over the two files located in the "NVflash 5.57" folder. Reboot your PC.

(note: use a bootable floppy disk with DOS files if you want if a USB key isn't available.)

Reboot your PC. Boot off your USB key. At the prompt type:

nvflash -save original.rom

When the process is complete, reboot your PC and boot back into Windows.

Step 2: Modify your BIOS

Open up NiBiTor. Click File > Open BIOS and select the BIOS file on your key. The window should look something like this:

Here is where you can change clock speeds for your card. I realized that the updated BIOS XFX sent me underclocked the shader clock by 50 MHz. :rolleyes: Time to fix that:

I took these speeds from EliteBastards's review of my card.

Notice the "Bootup clocks" button? DON'T change anything there. If you set the speeds too high you need to have the card at a safe level in order to reflash your original BIOS.

Click on the Temperatures tab, dismiss the warning, and click "Fanspeed IC." Now you should see this:

Mmkay, operating temperature's supposed to be 78C? :pinch: Whatever they thought was a solution to 8800 GT cards, well it didn't work. Let's fix that. Click on "Automatic speed." Here's what I think each option does:

• TCrit: The temperature Nvidia considers to be unsafe. Realistically this is when your card starts artifacting. ;)
  
• THyst: The difference of degrees separating the temperature needed to start ramping up the fans and the temperature needed to return the fan speed back to the minimum duty cycle.
  
• TMin: Your preferred minimum temperature setting. On my card I set it to 56C. Set it to suit whatever climate you live in.
  
• Min Duty Cycle: When your GPU's temperature is nice and cool, this will be the speed your fan spins at.
  
• TRange slope: Changing this controls whatever temperature is needed for full blast. I kept it at 20C. (NiBiTor spews an error message written in German at 26,67.)
  
• Acoustic enhancement: Delays the changing of fan speed by a given time interval.
  

A screenshot of my settings (TRange was changed after taking the screenshot):

Click OK, then File, Save BIOS. Give it a name like 'modified.rom".

Step 3: Reflash your new BIOS and test

Reboot your PC once more and boot off the USB key. At the prompt type:

nvflash modified.rom

Press Y to confirm. Once the process is done reboot back into Windows. Now fire up an intensive game and start testing. :)

If it all works, enjoy. You now get an overclocked card that will run at the speeds you choose on any OS, yes even Linux. If it doesn't work, reflash your original BIOS and try again.

Edited April 25, 2008 by rm20010

[cga]

Nice guide (Y) Will try it out as soon as i have gathered the guts. My 8800gts refuces to change the fan speed no matter how hot it gets, been experimenting with Rivatuner but it can be a real PITA to configure.

[Denis W. Veteran]

^^ Thank you. :)

Updated the guide a bit. This procedure will also work for overclocking.

[+shift. MVC]

I'm guessing this doesn't work for GeForce 9 Series cards?

[Raa]

Shift : I think it was updated to work with them, you'll need to check the readme first to make sure.

I'd advise you to use extreme caution using these tools, i've broken (and fixed) a few cards using them before :p

[Denis W. Veteran]

I'm guessing this doesn't work for GeForce 9 Series cards?

Geforce 9xxx is G92 based, like my 8800 GT. So yes, it'll work.