Turbo boost not working?


I just assembled the following system:

i5 2400
ASUS P8P67-M Pro
4gb ddr3 1333 (Gskill)
OCZ vertex 30gb
AMD HIS 6570
Corsair 430W V2 builder series

I am having issues getting turbo boost to work. I have updated the motherboard bios to the latest version, and I have set the multiplier in the bios to 38 (won't go higher).

This should get my 2400 to 3.5 when running prime95, right? However, I am only seeing 3.1ghz (measured with CPUid and Intel's turbo boost monitor).

I have built another system (i5 2500k) and am running that one at 4.2ghz with no problems. The theory should be the same, except for the multiplier limit of 38 on the 2400, right?

What am I doing wrong?
5 answers Last reply Best Answer
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  1. Hmm. Did you set all cores to 3.8? If so, that may be the problem (I don't KNOW that, but it would make some sense).

    Just looking at it (and I didn't know this, actually), 3.1 should be the stock 4 core Turbo speed, as well as the stock base speed (it goes 3.4 for 1 core, 3.3 for 2, 3.2 for 3, and 3.1 for 4), so 3.5 would be what the OC'd 4 core Turbo should be.
  2. OK so I figured it out -- there was a setting in CPU power management that I effectively disabled, and the board wouldn't go turbo.

    This particular board is weird. Running stock @3.1ghz the chip is only pulling 1.18v at full load. When turbo kicks in the vcore goes to 1.3!! This seems high as my other unit (2500k) runs 4.2ghz @ 1.24 vcore.

    This 2400 should be able to run at 1.2 and still hit 3.5 ghz, but the motherboard won't let me adjust the voltage. It seems to only want to run full turbo mode on its own terms (which is 1.3 vcore).

    Maybe its these quirky asus bios settings, but I can't figure out how to lower the turbo core voltage and maintain full turbo speeds. There is a setting that allows me to adjust the power, but it is measured in watts instead of volts (?!). When I do decrease this power setting the motherboard won't go to full turbo.

    Am I missing something here?
  3. Best answer
    Can you use the offset mode for voltage or is voltage adjustment just not available at all?
  4. Thanks for the help -- yes I was finally able to access offset mode but I had to disable some sort of power saving mode for it to even show up as an option.

    Turbo is running at 1.2v now. The cpu peaks at 3.6ghz, when running p95 (it switches between 3.5 and 3.6). I thought you could only go up four bins with this chip when running all four cores (i.e. from 3.1 to 3.5). Must be a glitch in the intel turbo boost monitor software.
  5. Best answer selected by diet_pepsi.
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