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Trial and Error

How To Overclock Your Graphics Card
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Since each individual chip has its own capacities, there’s no way to know in advance what frequency you can push your GPU to and still maintain stable operation. So, overclocking has to be done gradually – by increments of 20 MHz, say. You start by increasing the speed of the GPU (and the shaders). At each level, quickly test the stability of the system by launching an application that makes a lot of 3D demands, such as a game. It goes without saying that the rest of your configuration has to be perfectly stable before you can judge the quality of the overclocking of your graphics card. Too much overclocking will cause the game to simply crash, or else cause artifacts of various types (such as groups of pixels of the same color, refresh faults, untrue colors, etc.)

Once you’ve found the limits of the GPU, it’s time to tweak the memory. You can increase memory in slightly larger frequency increments than for the GPU – for example 50 MHz. If at some point you start seeing artifacts, go back to the previous level and bump the frequency up by a smaller amount (say 20 MHz).

RivaTuner Hardware Monitoring

Take care, though, because the frequency you feed into RivaTuner won’t always be the one it actually applies to the graphics card. On certain processors, including all GeForce 8s, the evolution of the frequency is not linear; it moves in stages. So, in our case, setting the GPU (Core) to 725 MHz or 735 MHz works out to the same thing – an actual frequency of 729 MHz. On the other hand, a change that appears slight can in fact cross a threshold and bump up the frequency by some 10 MHz. This somewhat delicate operation is not a real problem, since RivaTuner can check the actual frequencies. For that, go to the "Hardware Monitoring" menu (see above).

Average gains

In our case, the G94 of our reference GeForce 9600 was pretty cooperative. Clocked at 650 MHz from the factory, it was able to be increased to 767 MHz and remain stable. This had the shaders running at 1920 MHz. We tried desynchronizing, but were only able to gain 30 MHz. We were able to increase the memory from 900 MHz to 1116 MHz. On the bottom line, that works out to a jump of 18% for the GPU and shaders and 24% for the memory. Not bad, but not excellent either. It was enough of a gain, however, to catch up with the performance of an 8800 GT, which is 15% faster than the 9600 GT in its factory state.

9600 GT OC maxGeforce 9600 OC

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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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