How to Enable Intel Dynamic Acceleration (IDA) on Both Cores of a Core 2 Duo

Discussion in 'Windows OS and Software' started by unclewebb, Apr 21, 2010.

  1. unclewebb

    unclewebb ThrottleStop Author

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    Nando has assembled a list of special bios versions so a wide variety of laptop models now support Dual (IDA) mode.

    http://forum.notebookreview.com/6646598-post142.html


    I'd like to thank somebody over at TechPowerUp who introduced me to this little trick. :)

    Intel Dynamic Acceleration (IDA) on Core 2 Duo CPUs is designed so that the CPU will use a higher multiplier (faster speed) but Intel designed this feature so that only a single core at a time can benefit from this turbo boost. The second core has to be in the C3/C6 sleep state for this to work. As soon as the second core wakes up to process some background task; the maximum multiplier will drop back to the default multiplier. When the second core is finished and goes back to sleep, the first core can go back up to the higher speed by switching to the IDA multiplier.

    IDA mode is available in most of the T7000, T8000, P8000 and T9000 series of mobile Core 2 Duo CPUs.

    There is finally an easy way to enable IDA mode on both cores at the same time so it doesn't cycle on and off like Intel intended. When testing on a T8100, this resulted in a 9% performance boost when running the multi-threaded benchmark wPrime.

    Unfortunately, not all laptops are capable of enabling Dual IDA mode. You need to be able to toggle the SpeedStep (EIST) bit from within Windows. On the Dell D830 I tested, there is an option in the bios so you can disable SpeedStep / EIST but many manufacturers lock the EIST bit and don't provide any option to unlock it. If you don't have this bios option and ThrottleStop shows that the EIST bit is grayed out, that means it is locked and you won't be able to use this trick.

    Here's what worked for me.

    1) Enter the bios and disable Enhanced Intel Speedstep® (EIST).

    2) After you boot up, start up ThrottleStop. It should look something like this.

    [​IMG]

    The multiplier will be stuck at the default minimum which is 6.0. Adjust the multiplier to the highest possible value, set the Voltage ID which is the voltage your CPU will use and check the Set Multiplier box. Click on the Turn On button and then click on the EIST option. You should see the multiplier start to jump around in the monitoring area like this. If the multiplier is not above your default multiplier then make sure that you set the Minimum processor state to 100% in the Control Panel -> Power Options.

    [​IMG]

    The trick now is to disable EIST. This should force the CPU to lock both cores so that they will both be using the highest IDA multiplier. The T8100 I tested has a default multiplier of 10.5 and the IDA multiplier is 11.5. After I disabled EIST, the CPU multiplier gets stuck at 11.5 on both cores. :D

    You can run any sort of program you like and you can stress both cores as much as you like but it won't budge. By lowering the VID voltage to a safe and stable amount, you can run both cores at full speed without creating a lot of heat.

    The Intel 45nm T8100 I tested is so efficient that there doesn't seem to be any significant increase in idle power consumption when locked like this. With a Kill-a-Watt meter I couldn't measure any difference. It seems that at idle, the CPU turns itself mostly off no matter what settings you use so this little trick shouldn't significantly change idle power consumption or increase your CPU temperature.

    Here's the final result. Both cores are fully loaded while the IDA multiplier is fully engaged on both cores. Core temperatures look great too.

    [​IMG]

    If this trick works or doesn't work for you then post your results and let me know what type of laptop you have and what bios version it is using. Unfortunately some of the Acer laptops don't give you an option in the bios to disable EIST so you are out of luck.

    When EIST is disabled, ThrottleStop will not be able to control your multiplier anymore. It will still be able to monitor your CPU and you can use it to lock the clock modulation values but adjusting the multiplier and VID will have no effect. On my laptop, SLFM was also automatically disabled when I booted up with EIST disabled.

    If you want the operating system to get control of your multiplier then you will need to enable EIST before you exit ThrottleStop. I left it this way so once you set your CPU to use the IDA multiplier full time, you don't even need to leave ThrottleStop running. Your CPU will continue to use your locked IDA multiplier until you manually enable EIST.
     
    Kevin Henry and DooMaster like this.
  2. wontons

    wontons Notebook Consultant

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    Is there any downside to enabling IDA mode on both cores? There must be some reason Intel limited it to only one core at a time.
     
  3. moral hazard

    moral hazard Notebook Nobel Laureate

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    I believe intel did that to keep the CPU within it's quoted TDP.

    With IDA enabled on both cores, the CPU will be a little hotter.

    No real downside. I have been waiting for this for a long time, thanks unclewebb.
     
  4. Kuu

    Kuu That Quiet Person

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    I could try it on my laptop in my sig, but is there any real benefit to doing this apart from a slightly higher clock speed?
     
  5. maximinimaus

    maximinimaus Notebook Evangelist

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    My BIOS 1701 in an ASUS G71Gx has an option Intel Speedstep Tech which can be enabled/disabled. The explanation text says it is for GV3.
    I changed from enable to disable, but in TS the EIST bit is grayed out.
    CPU-Z shows that the T9600 CPU is running always at full speed, although I set Power Options to balanced mode.
    Is there any suggestion or advice?
     
  6. unclewebb

    unclewebb ThrottleStop Author

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    There won't be a huge difference in power consumption whether Dual IDA mode is enabled or not. Most Core 2 Duo processors have no problem at all running 100% reliably with the IDA VID voltage setting reduced. My T8100 has a default voltage of 1.1375 volts and an IDA voltage of 1.200 volts. It runs reliably in Dual IDA mode at only 1.050 volts. This drops power consumption to a lot less than TDP so you don't have to worry about damaging your CPU. You're doing it a favor.

    maximinimaus: Some motherboard bios versions will have features that don't work correctly. I have an older Asus desktop board and same thing. You can change some things in the bios but when you get into Windows and check, nothing has changed at all or EIST remains locked. The Dell D830 I used correctly leaves this bit unlocked when you disable SpeedStep in the bios.

    If ThrottleStop shows that the EIST bit is grayed out, that means the bios has locked it and there isn't any way to unlock it. Once locked, that's it. The only way to unlock the EIST bit is to reboot but in your case, the bios will immediately lock it again.

    [​IMG]

    I posted some power consumption numbers of Dual IDA over on this thread today.

    http://forum.notebookreview.com/showpost.php?p=6174500&postcount=4892

    If you use the IDA voltage on both cores then power consumption goes up but if you drop the voltage to the default VID, then Dual IDA mode does not consume any significant extra power compared to both cores locked at the default FID multiplier. Maybe 1 extra watt max on a 45nm Core 2 Duo CPU.
     
  7. unclewebb

    unclewebb ThrottleStop Author

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    ThrottleStop 2.00 Beta 17
    http://www.fileden.com/files/2008/3/3/1794507/ThrottleStop.zip

    I found Dual IDA mode to be so interesting that I decided to automate the process so it will be easier for users to check this out.

    If ThrottleStop shows that the EIST bit is not locked (not grayed out) then you can give this new feature a try. Just add this to the ThrottleStop.ini configuration file.

    DualIDA=1

    Your CPU needs to be lightly loaded for it to be able to switch into Dual IDA mode. If it is, this option will toggle the EIST status of your CPU until it is able to lock both cores of your CPU at the full IDA multiplier. On my T8100, this happens pretty much instantly.

    Set ThrottleStop up so the SetMultiplier option is checked and set to the highest value. Also set the VID voltage to an appropriate number. Once that is done then you can restart ThrottleStop with the above option.

    You can also try using the option DualIDA=2

    If ThrottleStop is able to lock both of your cores to the highest IDA multiplier then it will automatically exit since it has done its job and isn't needed anymore. Perfect thing to add to your start up sequence.

    The only problem so far is that if I use Stand By or Hibernate modes, the CPU will get locked at a 6.0X multiplier when I resume. It's easy enough to restart ThrottleStop to fix this problem real quick.

    I might automate this too in the near future so when it resumes, ThrottleStop will automatically lock your cores in Dual IDA mode again. :)

    Let me know if you see any issues and if it works for you.
     
  8. KingRaptor

    KingRaptor Notebook Evangelist

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    I have a Core 2 Duo T6400. According to wikipedia, this model along with all the Penryn Core 2 Duo's should have IDA.

    I also went into Control Panel --> Power Options --> Change Plan settings --> Change advanced settings and set the Processor power management to be 100% all the time.

    The problem is, my multiplier count still can't go above 10. Is this because I'm doing something wrong or because the T6400 can't go above 10x on the multiplier?
     
  9. maximinimaus

    maximinimaus Notebook Evangelist

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    Changing the powerplan to 100 % means the processor runs always with the highest multiplier, nothing else.
    Regarding IDA, the BIOS must support this feature. You can see in HWINFO32 if it's supported. My ASUS G71Gx BIOS unfortunately doesn't support IDA, although the CPU T9600 supports it.:(
     
  10. unclewebb

    unclewebb ThrottleStop Author

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    I can't find any data showing whether the T6400 supports IDA or not. If you start up ThrottleStop and the multiplier adjuster stops at 10.0 then that's as high as it goes and it definitely doesn't support IDA. ThrottleStop reads this info directly from the CPU.

    maximinimaus: I'm curious about your T9600. Does ThrottleStop let you access your IDA multiplier? I recently added an option to toggle the "Disable Turbo" bit. Usually if that is unchecked and you set the ThrottleStop multiplier to its maximum then you can access your IDA multiplier. Can you post a screen shot of ThrottleStop while running a single threaded benchmark like SuperPI mod. Take a screen shot about half way through a 1M calculation if you can. I haven't seen a bios yet that could block IDA. There are two different bits in the CPU that can disable IDA. If ThrottleStop can't get this working for you then let me know and I will come up with a plan B you can try.

    Generally speaking that's true unless you're using the Power Saver option in ThrottleStop. This option over rides that so you can set the Power Plan to 100% and have ThrottleStop in charge of lowering the multiplier at idle.
     
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