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Overclocking ATI: Radeon HD 3850

How To Overclock Your Graphics Card
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Gigabyte GV-RX385512HAfter we’ve forced all these pages with a strong Nvidia coloration to them on you ATI fans, it’s finally time to look at how to overclock a Radeon. We chose the Gigabyte HD 3850 from our reference system for the occasion. This card has a very good performance/price ratio, and it’s tempting to try to improve it even more by overclocking it.

Overclocking a Radeon is very similar to the process you use for a GeForce. So we recommend that anybody who has skipped the preceding pages go back and read them, since they’ll be in a better position to understand what follows if they do.

Overdrive or Overclocking for Dummies

The first step is to do a software-based overclocking, as described above. There are several choices for doing this. The first is the official AMD drivers. The Catalyst drivers include an "Overdrive" tab that’s pretty well designed. The first time you launch it, you’ll have to unlock access to the control panel by clicking the lock button.

ATI Catalyst OverdriveCatalyst OverDrive Auto-Tune

Once you’ve done that, there are two possibilities: You can enter the frequencies for the GPU and memory yourself, or you can let the “Auto-Tune” function do it. We opted for the second approach. Auto-tune is effective and very convenient. It increases the frequencies in small steps and automatically tests stability at each step. When it’s found the maximum the card can handle, it moves back a step so as to ensure fully reliable operation, at the expense of a little performance. This makes Auto-Tune the ideal solution for beginners, and it’s also a way of “roughing out” further tweaking, since the automation saves a lot of time.

AMD Overdrive autotune

We hereby award another good point to the Catalyst drivers: As soon as you enter your changes, the overclocking settings are automatically recorded and reloaded at each boot-up, without having to tinker with any additional settings. What’s more, you keep the Radeon-specific PowerPlay system, which lowers the card’s operating frequencies when you’re only running 2D. So most of the time, our Radeon HD 3850 was running at only 297/693 MHz, instead of 670/700 MHz.

Easy but Limited

The Auto-tune feature of Overdrive let us push our Gigabyte Radeon HD 3850 from 670/700 MHz (GPU/Memory) to 719/870 MHz (715.5/864 MHz actual). And all in less than three minutes. Note that the memory of our Gigabyte card was abnormally slow from the factory, since ATI recommends 833 MHz for the memory on its Radeon HD 3850s. So the gain wasn’t much on the memory, and not really much more for the GPU. The latter is an RV670, which runs at 775 MHz on the Radeon HD 3870, so we were hoping for better. For that, we’ll have to forget Catalyst, which won’t let us set the GPU frequency above 730 MHz.

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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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