How to change your 6800GT 256mb voltage

I'm sorry if this has already been posted, but i just accomplished this on my friend's PC, and increased overclockability on the core by 30mhz, so thought that i might share it.

For all 6800gt owners, besides Gainward Golden Sample, and Asus owners, your 6800GT video card's core voltage in 2d mode is 1.2V and 3d is 1.3V. As some of you probably know, to get good overclocking results on a CPU requires to raise the Vcore, well on the video card it's the same thing. Raising the voltage on your 6800gt from 1.3V to 1.4V gives significant results, however not all cards can handle this, after reading some forums, many brands of cards cannot handle the slight increase in voltage, the 2 brands that are almost guranteed to fail are BFG and PNY, but you could still give it a try.

This process is fairly simple, and in my opinion foolproof, but just in case you do screw up, you can always flash it back using a PCI card to boot computer.

Okay first of all you'll need the following things,
1. Floppy drive
2. Floppy disk
3. Download the program <A HREF="" target="_new">NiBiTor</A>
4. Download the <A HREF="" target="_new">NVflash</A> utility
5. Balls

First to back up your original bios:
-Create a bootable floppy disk, then copy the NVflash files onto the floppy.
-Set computer to boot from floppy in bios
-after the floppy disk has loaded, type "a:nvflash -b backup.rom" without quotes, then press enger. this will save your current bios on the floppy as backup.rom
There you've backed up your current bios, in case the new bios doesn't work out just flash back to this.

Now reset computer and go back into Windows, open the backup.rom file on your floppy disk using NiBiTor, now press the voltage tab, and set the 3d voltage from 1.3V to 1.4V, now save the file on the nvflash floppy you just made as newbios.rom

Here's how to flash your card with the new bios:
-Boot from the floppy with NVflash and the newbios.rom
-After floppy's loaded type "a:nvflash -p -u -f newbios.rom" without quotes, and press enter.
-Reset computer, and go into windows, it shouldn't have problem with driver, since you only modfied your own bios.

You're done, you just increased the core voltage to 1.4V on your card, happy overclocking.

Now if the card behaves strange in any way in coolbit, such as crashing when you press the test button, that means your card sucks and can't handle 1.4V, flash back.

Here's how to flash back to original bios.
-Boot from nvflash with backup.rom floppy
-type "a:nvflash -p -u -f backup.rom" without quotes and press enter.

I think i covered everything, if i remember anything else i'll update this. This is a very simple process, and can't go wrong, so if you got all the stuff i said you'd need, then give it a try. If your card sucks and doesn't work out, hey just flash it back, you got nothing to lose.

Okay, have to mention this in the end, if you're a dumb@ss and screw up your card, I am in no way responsible, you do this at your own risk.
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  1. Oh forgot to mention, this is for the AGP version only.
  2. Nice info as always. I haven't seen it posted before, and even if it were, then definitely worth repeating for the Tweakers. :cool:

    - You need a licence to buy a gun, but they'll sell anyone a stamp <i>(or internet account)</i> ! - <font color=green>RED </font color=green> <font color=red> GREEN</font color=red> GA to SK :evil:
  3. Yeah this is basically modifying the GT core to the Ultra core, my friend's EVGA 6800GT couldn't stabilize at 430mhz before, after this, it not only stabilized at 420, but it went all the way up to 440mhz stable. 3dmark03 for a whole night with full aa/af.

    I'm screwing around with my PCI Express 6800ultra, trying to modify the voltage from 1.4 to 1.6, so far it's all been failures. I guess maybe they just can't take that much voltage.
  4. The only type of failure i've seen so far with bios voltage mod, is that BFG and PNY doesn't operate with more than 1.3V, because they just can't regulate more power.
  5. The only type of failure i've seen so far with bios voltage mod, is that BFG and PNY on the 6800GT doesn't operate with more than 1.3V, because they just can't regulate more power.
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