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I have a Samsung Series 5 laptop with an Intel Core i5-2467m process @ 1.6Ghz. The processor supports Intel Turbo Boost up to 2.30 Ghz according to the specifications. The i5-2467m is a dual-core process with HyperThreading, so there is a total of four (4) virtual cores in Windows 7 SP1.

I've installed the Intel Turbo Boost Technology Monitor v2.6 to monitor if Turbo Boost is enabled, and set it to "Always On Top."

I followed this process to max out the CPU:

  1. Open (4x) PowerShell instances
  2. Set each instance's affinity to a distinct CPU vCore
  3. Ran this code in each instance: while (1 -eq 1) { }

Unfortunately, after maxing out all 4 cores, my laptop got hot, but Turbo Boost never kicked in.

Any ideas on how to ensure that I'm getting the 2.3Ghz Turbo Boost capability of my laptop?

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"Unfortunately, after maxing out all 4 cores, my laptop got hot" That's probably why Turbo Boost didn't kick in - your laptop's cooling system cannot handle overclocking all four (virtual) cores. What happens if you run just one or two PS instances? – Indrek Jul 1 '12 at 20:46
I tried a bunch of lighter tasks, but never saw it activate. After rebooting the unit, it finally started working. – Trevor Sullivan Jul 1 '12 at 21:22
up vote 4 down vote accepted

Turbo boost is supposed to boost the CPU speed within thermal limits, if only one core is in use but the thermal limit is not met then Turbo Boost will boost the CPU speed for short periods.

By trying to load all 4 cores you are most likely surpassing the thermal limit and thus preventing it from activating.

As per Wikipedia:

The increased clock rate is limited by the processor's power, current and thermal limits, as well as the number of cores currently in use and the maximum frequency of the active cores. When workload on the processor calls for faster performance, and the processor is below its limits, the processor's clock will increase the operating frequency in regular increments as required to meet demand. Frequency increases occur in increments of 133 MHz for Nehalem microarchitecture processors and 100 MHz for Sandy Bridge microarchitecture processors. When any of the electrical or thermal limits are reached, the operating frequency automatically decreases in decrements of 133 MHz/100 MHz until the processor is again operating within its design limits.

That Wikipedia page also shows some examples of Turbo Boost functioning and as more cores are in use the boosted speed is lower.

Try running only 1 worker thread and keeping your laptop as cool as you can, then Turbo Boost should activate.

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Good answer, but I think it just needed a reboot. I saw another question on SuperUser that indicated there might be a problem with Turbo Boost after resuming from a low power state (which I had done previously). I am wondering if there's a bug with the Samsung Series 5 also. – Trevor Sullivan Jul 1 '12 at 21:23
No worries, without knowing that you'd gone into suspend lately we couldn't know if it was a factor and you wouldn't have known it was relevant. It is a bug i've heard of before though and I'd assumed it would have been fixed by now. – Mokubai Jul 1 '12 at 22:13
@TrevorSullivan Not that I'm complaining about the accept (I like the rep) but if your self-answer is correct then feel free to mark it as such. My answer might help some people in future but your answer is right for you. If you need me to edit my answer in order to get the system to release the accept-lock then let me know. It may still be a day or so before you can accept your own answer though as that's the way the system works. – Mokubai Jul 2 '12 at 18:12
Cool, well it'll let me accept my own answer tomorrow. If I remember, I'll change it, otherwise enjoy! :) cheers – Trevor Sullivan Jul 2 '12 at 18:13

I rebooted my laptop to solve the problem. My best guess is that it got broken during a low power state.

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