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Good evening, I have a new Core i7-based Sandy Bridge machine. The machine was overclocked by the system builders so that it should run at 4.6Ghz when a single core is under load. However, the suggested method for confirming this given by the suppliers was to run Prime95 and CPU-Z - these are Windows applications, whilst I am using a Linux (Ubuntu 11.04) environment. Having done a fair amount of internet searching I'm unable to find a canonical way of confirming in Linux that the "turbo" is taking place when the single core is under load.

This is quite important to me as I'm running computational physics calculations on the machine and need it to be as quick as possible.

Any help would be most gratefully received, please let me know if I've not been clear enough in my explanation.

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If these are reliable, deterministic calculations, you might just consider running them with the overclock enabled and disabled and comparing the runtimes. –  Shinrai Jun 6 '11 at 18:16
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4 Answers

Use MPrime. It is the same as prime95, but its for linux. See here for slightly more info.

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Thanks, but I guess my question is more along the lines of how can I see the CPU clock rate, rather than how can I max out the CPU. –  endian Jun 6 '11 at 18:57
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You should be able to find out your current cpu speed with the command

more /proc/cpuinfo | grep MHz

Remember that the 4.6GHz speed is when your maxing out one core, if your test program is using several cores you probably won't see speeds that high.

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Thanks. Unfortunately cpuinfo only displays the standard frequency (3400.509 in my case) regardless of whether the system is under load. The program only uses one core, so I would expect the system to enter the overclocked state. –  endian Jun 6 '11 at 19:42
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up vote 2 down vote accepted

After a great deal of searching, forum posts and dead-ends, I finally discovered the tool "TurboStat", which is capable of reading the CPU frequency. It's in source-code form, the link is here: http://www.kernel.org/pub/linux/kernel/people/lenb/acpi/utils/pmtools-latest/turbostat/turbostat.c

Other tools that I tried and failed to use: cpufreq, cpupowerutils

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CPU-G is the linux equivalent to cpu-z for windows: http://www.webupd8.org/2009/10/cpu-z-for-ubuntu-cpu-g.html

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please give an explanation in your answer.read the FAQ. –  Shurmajee Feb 20 '13 at 9:05
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