Some info about MacPro’s 2600XT and possible powerplay support.

it maybe usefull information for owner of radeonhd 3800/2600 card with overheating problem.

after digging a bit i managed to open 2600XT mapro’s bios image in Radeon Bios Editor


and here is screenshot about supported state (which is for powerplay)

Free Image Hosting at

so idea is to try to edit Mhz for 2d state. good luck

Do it on your own risk.


  1. mitch
    March 21st, 2008 | 12:38 am

    With OS X the Desktop (2D) is using QpenGL (3D) for faster Screenoutpu (QE).
    Does reducing 2D clocks helps than ?

  2. macosx77
    March 21st, 2008 | 2:09 am


  3. netkas
    March 21st, 2008 | 1:28 pm

    mitch, it’s apple’s problem, if they did it for macpro’s 2600XT, then it may work fine for other hd cards

    anyway, need to check

    OSX’s window system doesn’t make VERY intensive gfx usage i think

  4. mitch
    March 21st, 2008 | 3:59 pm

    I will try to change same thing on my NV 7600gt (set 2D clock down).

  5. Fritz
    March 21st, 2008 | 6:15 pm

    Thanks for the last natit! My HD3870 works fine, but (although still almost noiseless) the fan rotates a bit fast. The cards seem to consume quite a bit of power unnecessarily. I don’t want to hack the bios however, since I also use the card under XP and I’m afraid of breaking something. But thanks for the info about the latest developments. =)

  6. March 21st, 2008 | 10:33 pm

    well, i tried and tried and tried… at the end i set every clock to 200Mhz… The Result was the same (windows showed 500/600) and xbench gave me same results.. dumping the modded bios off the card to see if the clocks were really set.. they were..

    not sure why this didnt work out…

    i still gotta think about the natit file wich had the bios implemented… still a nice way to tweak and try etc..

    maybe some kind of external tool wich lets you choose various bios files to load with natit… maybe via boot flag… would be cool.

    go for it!

    no need to flash for real aswell, very secure feor teh n00b

  7. Fritz
    March 22nd, 2008 | 2:20 pm

    Yeah something like Rivatuner for OSX would be cool. Then you could low-level tweak fan-settings and even softmod ATI gamer cards into FireGL equivalents (as it happens here:

    Guess that would be alot of work, but I’d even pay for it. =)

  8. netkas
    March 23rd, 2008 | 4:08 pm

    i lowered my 2d state to 115 for GPU and 1.05 Vcore and 2XX Mem mhz

    so, in windows it works Great, in osx it makes it to boot gui in 2 mins.

    not good..hmm

  9. Lion
    March 23rd, 2008 | 4:53 pm


    I have a Radeon HD 2900pro and also have the hot/loud problem. Seems like the card is running in 3D mode all the time. I allready lowered my 2D clock to 300/300 at 0.85V (instead of 500/800 at 1V). In Windows the card is now perfectly quiet and does not consume that much power anymore.

    However, in OSX it runs in 3D Mode and the fan spins up. Not good.

    Is this only a problem of some cards or is it a gerneral problem of all Radeon HD cards?

    I would be willing to change my gfx card if that would solve the problem. But which one can I use?


  10. March 23rd, 2008 | 8:19 pm

    windows guy is pure 2D…
    OSX is running openGL = 3D… no half 3D no 2D… full 3D..

    isnt it? makes sense to me atleast…

    gfx cards even wouldnt get hot if it would be 2D…
    not to mention that the problem wouldnt be there…


  11. Lion
    March 23rd, 2008 | 9:13 pm

    So I tested some more and my card (2900pro) is definitly running in 3D high power mode.

    I lowered clock for 2D and low power 3D mode. Card is completly quiet in Windows now. But in OSX the fan goes crazy… pls help!


  12. fartq
    March 23rd, 2008 | 10:30 pm

    i’ve read that osx implements a demand pager for vram under QE/CI and QGL. this might be extremely sensitive to memory bandwidth. what happens when you leave memory clock at full speed and drop gpu vcore/clock?

  13. netkas
    March 24th, 2008 | 6:18 am

    Radeon 2900 can use only franklin framebuffer driver, and PowerPlay isn’t implemented there.

    Hmm… i will try lowering mem Freq a bit, to 500 e.g.

    About OGL and 2D, it’s apple’s/ati’s problem, not ours, of they made it in tehre cards, then it should work fine (if it will work) for us

  14. fartq
    March 24th, 2008 | 8:26 am

    it looks like the way that powerplay is implemented, the graphics driver just has some two bit register it can flip to make the card run at one of four “power profiles” set in BIOS (the ones in the gif), so it’s entirely possible that the 2000 series mac driver throws the card into 2d mode when only rendering QE.

  15. netkas
    March 24th, 2008 | 9:16 am

    state depedns on gpu loading, not ogl used or not, from what i learned in ioreg, for x2000 lower limit set to 12%

    so, under 12% gpu usage it will sue 2d state.

    i set 230/460/1.1 for 2d state, seems to work withotu boot lag.

    dunno how to test 2d state freq lowering.

  16. fartq
    March 24th, 2008 | 9:51 am

    do you have a power consumption meter of any kind?

  17. Lion
    March 24th, 2008 | 1:15 pm

    « netkas: So the 2900pro is not fully supported? I noticed some freezes when I changed the size of coverflow or videos. So if there is no chance to get a 2900pro working quietly and correctly, I should get another card, right?

    Do ou know if this problem (powerplay) also occurs with 3870 cards? Or what about nvidias 8800gt? Are these two cards fully supported (i.e. no freezes etc and original apple fb?).

    Thank you 🙂

  18. Lion
    March 25th, 2008 | 1:41 am

    The wired thing is – even when I lower the clock for all states available in RBE.exe and lower the fan settings it does not work.

    The fan is still spinning up in OSX even though the card should have the same low clock and voltage setting in 3D as in 2D mode. In Windows it works just fine, the card runs with 300/300 at 0.85V all the time and does not speed up in 3D mode anymore. Perfectly quiet.

    But in OSX it is sooo noisy.

    Seems like the driver is overwriting the cards BIOS settings. To bad we do not have a programm able to show the actual clock settings.

    Eventually it is not only the noise but also the high power consumption comming with the noise. My Computer is running all the time.

    Any hints?


  19. quizas
    March 27th, 2008 | 10:46 am

    And who can help us 2400xt(94c8) users?
    Neither triakis nor natit will work.

  20. John Smiley
    March 28th, 2008 | 7:08 pm

    Has anyone tried taking the Apple Update supplied 2600 Firmware Update and tried flashing a 2600 XT with the bios supplied within. Maybe with RBE from windows?

  21. sama7896
    April 17th, 2008 | 1:02 pm

    hi, i have a HD 2600 pro, and i have some noise problem, in windows the card performs really quiet, but on mac it makes a lot of noise, sppeds up then slows down, sometime the system crashes(about the time it slows down). This only happens on first boot, when it warms up, then it is still noisy but constant. What can i do ? Any sugestions ?
    Thanks netkas

  22. SG
    April 19th, 2008 | 4:54 pm

    any updates on this? i just went from a 8800gt to a 3870 because i was sick of the poor OSX nvidia drivers (hard lock ups some times with complicated shaders active and the driver/kernel coughing up with NV timeouts)..

    i’m using the 10.5.3 so maybe these new drivers do something, and while the card is louder than my 8800gt while just doing 2D it does get louder when i’m playing games or doing some 3D, so maybe its fixed in .3 or maybe the 3870 acts differently.

    one thing i’ve noticed is with dark colors on screen (like a big dar grey or near black color) you can see some wavy motion happening… i havent booted in windows yet to see if i get it but im starting to wonder if this card is slightly bad or if 3870s are just like this.

  23. Cristian Tacchi
    October 23rd, 2008 | 2:01 am

    netkas.. i have osx 10.5.5 from ideneb.. with it almost everything works.. except QE/Ci on my sapphire HD2600 pro 512mb (id: 9589).. when i modify info.plist and reboot. it givesme

    a> one black monitor and another strippe lines all over the screen..
    b> a blue screen on both monitors with two mice cursors (just one moves)..

    anyway.. i dont know how to repair it to continue trying.. it does not boot even in “-x” safe mode..

    and i dont know what to do.. the files you have works on 10.5.5??

    thanks for your time..

  24. Jobauma
    November 5th, 2008 | 9:11 am

    I have a HD 2600 XT, and as I clocked down the bios yesterday, that didn’t fix the problem, the system was still freezing after a while. That made me go for the original MAC Pro’s bios image, but today there seems to be no more problems anymore for some reason. RIGHT after all the system freezes there was yesterday, I tested if the fix worked, so the graphics card was probably too hot for any difference to notice. I guess that’s why my computer has been running for over an hour now.

    Because the newest version of Radeon Bios Editor (1.17) was different from the attached picture, I’m not sure if I clocked the bios right, but my computer has in fact been running like nothing before…

    …so one thing that remains is watching a movie.

    Thanks for your instructions.

  25. Jobauma
    November 6th, 2008 | 8:37 am

    Well, once I was watching a movie it took about 15 minutes or so for the system to crash, but without movies my computer was running all day, so the clocking has definitively done something.

    What shall I do? Is it recommended to clock down the bios some more, or will that help?

  26. Jobauma
    November 8th, 2008 | 12:00 am

    The solution was to remove a sound card (I wasn’t using) that made no space between it and the fan for the graphics card. Weird that I didn’t need to do that while running Vista, and neither did I need to clock down.

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