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

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.

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.

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.

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.

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.