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In the BIOS with NiBiTor

How To Overclock Your Graphics Card
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As a preamble, we should make one point very clear: Before making any change to the BIOS, the card’s stability with the frequencies you’ve chosen has to have been checked first using the software route. If you push your card too hard, you could end up with no display at all, and it won’t be easy to go back. Also, of course, you should make sure that nothing interferes with the operation of your computer during the four seconds the flashing takes, or else you could end up with an unusable card on your hands.

The Limitations of NiBiTor

Once you’ve determined the highest frequencies your card can tolerate using RivaTuner or nTune, it’s tempting to hard-wire them into the card’s BIOS. To do that, the first thing you need is a BIOS editor. For GeForce cards, the program you need is NiBiTor (Nvidia Bios editor). Once you’ve installed the software, the first step is reading and backing up the card’s original BIOS settings, via the "Tools" menu, "Read Bios," "Read into File." The name of the BIOS file must be a maximum of eight characters long, with no accented characters allowed – for example: 9600base.rom.

nibitor

Once you’ve backed up the BIOS settings, you can change them. The default tab shows four different sets of frequencies – "Extra," "3D," "Throttle" and "2D." 3D and 2D need no explanation, but Extra and Throttle are more mysterious. Throttle designates the frequencies the GPU is to drop to when it detects a temperature that’s too high. Extra is in fact a new mode introduced by Nvidia with the GeForce 8 series, which made the preceding ones obsolete. It’s because of this Extra mode that the latest GeForce 8s no longer automatically change their frequency for 2D and 3D. Of course we tried to get around that. First we tried adding 2D frequencies in addition to Extra, and then even deleting the "Extra" frequencies and replacing them with 2D and 3D frequencies, but none of those tactics worked. The card kept operating at the "Extra" frequencies all the time.

Nibitor overclocknibitor fan

We also hoped that NiBiTor would give us a lot of control over ventilation. Like RivaTuner and nTune, NiBiTor allows you to control other parameters than the card’s clock frequencies. Thermal regulation is hidden in the "Temperatures" tab. But none of the settings we made there had any effect.

Have a floppy handy?

So, the only change we were able to make to the BIOS was to switch from the original "Extra" frequencies – 650/1625/900 MHz – to 767/1950/1116 MHz. Once the BIOS settings have been changed, you have to save them under a clearly identifiable name, for example “9600OC.rom.” Then you need to save the file to a bootable medium. That’s because the flashing can’t be done under Windows; you have to re-boot to a DOS volume. Which volume? Well, a diskette, for example. What? You don’t mean you’ve sacrificed your good old 3.5" floppy drive on the altar of modernity? Well, don’t panic. It’s possible to format a USB key to make it bootable. The simplest method is to use a little utility you can get from HP, downloadable at. This program automates the creation of a bootable USB key by copying the Windows 98 DOS system files to it.

Once the key or diskette is properly formatted, copy the edited BIOS file to it. Make sure and copy the backed-up original, so that you can go back if something goes wrong. Finally, copy the NVFlash utility to your media; its name should tip you off as to what it does. It’s this program that will do the flashing of the EEPROM itself. After you reboot, enter the following command line:

nvflash -4 -5 -6 9600OC.rom

Press Enter, and... voilà!

NVFlash 9600GTFlashage Geforce

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  • 0 Hide
    jimmysmitty , April 24, 2008 5:35 PM
    I OC'ed my HD2900Pro 1GB to a 850MHz GPU (from 600MHz) and 2250MHz memory (from 1850MHz). So I technically got alomost a 50% OC. But mine is just a HD2900XT 1GB just down clocked.
  • 0 Hide
    brendano257 , April 24, 2008 8:23 PM
    The HP disk utility asks me for DOS files to write to the disk where would I find these?
  • 0 Hide
    Shadow703793 , April 24, 2008 8:36 PM
    To any one interested in modding nVidia BIOS:
    http://www.tomshardware.com/forum/forum2.php?config=tomshardwareus.inc&cat=29&post=246611&page=1&p=1&sondage=0&owntopic=3&trash=0&trash_post=0&print=0&numreponse=0"e_only=0&new=0&nojs=0
  • 1 Hide
    randomizer , April 25, 2008 2:01 AM
    Better than the "Overclock your card in 5 minutes" article.
  • 0 Hide
    randomizer , April 25, 2008 2:13 AM
    By the way, the first step in Nibitor is to select the device, before you can read the BIOS ;)  I'd like to know how you "deleted" the "Extra" frequencies. Did you set them to 0 or did you actually set the number of performance levels to 3 instead?
  • 0 Hide
    jojesa , April 25, 2008 4:43 AM
    brendano257 visit www.bootdisk.com and get those files.
  • 0 Hide
    randomizer , April 25, 2008 8:27 AM
    A good idea for doing blind flashes is to have a second floppy (with the DOS files on obviously) but add a file called autoexec.bat with the following line in it:

    nvlfash -4 -5 -6 -a -y file.rom

    where file.rom is the filename and it could also be a .bin file. That will flash the card without you having to hope you typed it in right, just make sure you gave it a good minute or two before restarting so you don't corrupt the BIOS.
  • 0 Hide
    randomizer , April 25, 2008 8:32 AM
    Typo correction - the line in the autoexec.bat file should read:

    nvflash -4 -5 -6 -a -y file.rom

    Why can't I edit my own comments?
  • 0 Hide
    matthieu lamelot , April 25, 2008 8:43 AM
    randomizerBy the way, the first step in Nibitor is to select the device, before you can read the BIOS I'd like to know how you "deleted" the "Extra" frequencies. Did you set them to 0 or did you actually set the number of performance levels to 3 instead?


    Setting them to zero wouldn't work, you have to set them to dash ( - ), as you can see in the screenshot on page 6. AFAIK, Geforce 8 won't boot correctly if you suppress their "extra" performance level.
  • 0 Hide
    perzy , April 25, 2008 9:27 AM
    with the really extremly bad cooling on todays GPU's ...a little plastic fan with sleeve bearings that runs slower and slower before it stops completly.. i'm very cautious. New cooling? Yeah, but that costs and then i get a 10% oc. Hmm.
  • 0 Hide
    randomizer , April 25, 2008 9:29 AM
    matthieu lamelotSetting them to zero wouldn't work, you have to set them to dash ( - ), as you can see in the screenshot on page 6. AFAIK, Geforce 8 won't boot correctly if you suppress their "extra" performance level.

    It's worth a try, you might get lucky. ;)  Besides, you can always blind flash back. Try setting the number of performance levels to 3 (first ticking the "change amount of active performance levels" box of course).
  • 0 Hide
    randomizer , April 25, 2008 9:31 AM
    perzywith the really extremly bad cooling on todays GPU's ...a little plastic fan with sleeve bearings that runs slower and slower before it stops completly.. i'm very cautious. New cooling? Yeah, but that costs and then i get a 10% oc. Hmm.

    So you want them to jack the prices up more? We get ripped off as it is until a year after stuff get's released.
  • 0 Hide
    radium69 , April 25, 2008 10:40 AM
    benchmarks anywhere? i'd like to see performance in gaming benchmarks. Fairly interesting article. Could save me some $
  • 0 Hide
    randomizer , April 25, 2008 10:56 AM
    The performance benefit is usually
  • 0 Hide
    matthieu lamelot , April 25, 2008 1:54 PM
    radium69benchmarks anywhere? i'd like to see performance in gaming benchmarks. Fairly interesting article. Could save me some $


    Performance is as you would expect it to be : fairly on par with the frequency increase. Don't expect miracles here, but it's enough to climb one step on a manufacturer's performance scale. i.e. our overclocked Geforce 9600 GT was as fast as a regular 8800 GT. Of course you could go beyond that, should you manage to reach higher frequencies than us (better card, better cooling, voltage mod, etc.)
  • 0 Hide
    Junkdude75 , April 25, 2008 7:59 PM
    My Radeon 2900 pro 512MB,
    went from 507Mhz GPU and 514Mhz memory
    to 846Mhz GPU and 890MHz memory.

    Thank you fore the ispiration!
  • 0 Hide
    randomizer , April 26, 2008 12:45 AM
    You got a nice overclock on that 9600GT. Mine won't play nicely in Crysis until I drop to 750MHz. Unfortunately ATITool can't detect artifacts no matter how much they fill the window with yellow, but just looking for them myself I didn't see any at 770MHz. Crysis just caused driver crashes all the time, which fortunately recovered every time. I only have my memory at 936MHz, I don't know how high I can go with that, but probably not far. The same crashes occur with the shader clock above 1770MHz. This was done via rivatuner with 174.74 drivers.

    Just to let you know, the coders of NiBiTor are working on fan control, but they don't have enough 9 series BIOSs (especially 9600GT).
  • 0 Hide
    chovav , April 27, 2008 9:36 AM
    I got my 8800GT overclocked from 600Mhz Core to 691Mhz, 900Mhz memory to 1065Mhz and Shaders from 1500Mhz to 1728Mhz. It also ran stable at 700/1100/1750 but I decided to choose a little safer settings to flash the bios with. This overclock of about 17% gave me 16.3% better performance in 3D Mark 06! all that in no time! Thanks guys!!!
  • 0 Hide
    ferreguetti , April 27, 2008 11:56 PM
    Well you don't really need a floppy and it's really rare and hard to use it, what I did was, I have a windows 98 installation cd and i used that, works just fine...
  • 0 Hide
    randomizer , April 28, 2008 12:11 AM
    It's hard to use a floppy? I find it easier than using CDs, there's one less button to push. They are just real slow.
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