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Is there any way to check at which clock speed my processor is running?

I have already tried cat /proc/cpuinfo but the clock speed I'm running isn't showing. I know Ubuntu 12.04 (Precise Pangolin) requires 700 MHz and VGA, but will an AMD Mobile Sempron work?

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You need more specific on the second part of your question. Do you know the model number? – LiveWireBT Nov 20 '12 at 6:55
Thank you for all the answers but I am good now! – user1610406 Nov 20 '12 at 23:04
up vote 74 down vote accepted

From the command line type lscpu. The information will be at CPU MHz:

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Note that the value of CPU MHz is not fixed and may change by the second. – Cerin Jan 30 '14 at 15:53
If you'd like to have it update in real-time, this will help: watch -n1 "lscpu | grep 'MHz' | awk '{print $1}'". – Amal Murali Nov 16 '14 at 14:39
@Ivan: Sorry, disregard that. The output of this command: watch -n1 "lscpu | grep 'MHz' | awk '{print $1}'" – Amal Murali Dec 21 '15 at 20:52
@Ivan: Okay, here you go: watch -n1 "lscpu | grep 'CPU MHz' | awk '{print $1}'" – Amal Murali Dec 21 '15 at 22:47
@Ivan: For a momentary observation, you don't need watch. This would do: lscpu | grep 'CPU MHz' | awk '{ print $3; }'. I'm not sure about the exact output you're getting on your system. I'll explain the command if that helps: first lscpu gets the full output that contains information regarding your CPU, grep then searches for CPU MHz and prints out just that line, awk takes out the $N-th block and displays it out. And if you want the result to change in real-time, then wrap the command in a watch -n1 "...". – Amal Murali Dec 22 '15 at 10:51

There are a couple of ways:

  1. lscpu or more precise lscpu | grep "MHz".
    This will give you the general MHz for the CPU.

    $ lscpu | grep "MHz".
    CPU MHz:               1600.000
  2. cat /proc/cpuinfo or more precise cat /proc/cpuinfo | grep "MHz".
    This will give you the individual MHz for each CPU Core. So if you have an Core 2 Duo, AMD Bulldozer, Core i7, etc.. it will show the MHz for each core.

    $ cat /proc/cpuinfo | grep "MHz"
    cpu MHz     : 1600.000
    cpu MHz     : 1600.000
    cpu MHz     : 1600.000
    cpu MHz     : 1600.000
    cpu MHz     : 1600.000
    cpu MHz     : 1600.000
    cpu MHz     : 1600.000
    cpu MHz     : 3400.000
  3. lshw -c cpu or more precise version: lshw -c cpu | grep capacity
    Will give you the general MHz. Same as lscpu.

    $ lshw -c cpu | grep capacity
    WARNING: you should run this program as super-user.
           capacity: 1600MHz
    WARNING: output may be incomplete or inaccurate, you should run this program as super-user.
  4. sudo dmidecode -t processor or more precise: sudo dmidecode -t processor | grep "Speed" Will not only give you a MHz in use but also the Maximum you can push / overclock your CPU to.

    $ sudo dmidecode -t processor | grep Speed
    [sudo] password for cyrex: 
        Max Speed: 4000 MHz
        Current Speed: 2666 MHz

Out of all of this, lshw and dmidecode provide the best information out of your CPU.

You can also target the current MHz detected by the kernel by querying the log files:

cat /var/log/dmesg | grep "MHz processor" - For the current detected MHz speed

cat /var/log/kern.log | grep "MHz processor" - For the current and past detected MHz speeds. Will not work in some cases, that is why I posted the dmesg one first.

And that's all I can remember from the top of my head. I am fairly certain there are other ways, just don't remember right now. Of course, talking about terminal ways.

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For me, all options except dmidecode gave a false reading: I'm overclocking an intel E6600 2.4ghz chip on a gigabyte ga-965p-ds3 3.3 board with 7x multiplier & 400mhz CPU frequency to give 2.8ghz CPU, but the stock multiplier is 9 (9x266=2.4ghz) so I suspect the rest of the tools assume multiplier is stock and times that by the CPU mhz, so in my case they all give 3.6ghz. – dez93_2000 Oct 31 '14 at 22:30

For the current CPU speed one can dynamically watch this change in real time using:

sudo watch -n 1  cat /sys/devices/system/cpu/cpu*/cpufreq/cpuinfo_cur_freq

To see the maximum CPU speed, use:

cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_max_freq 
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+1, I know this is an Ubuntu site, but this appears to be the only answer providing a command that is completely OS independent. – Andy E Apr 24 '14 at 11:53
If you get Permission Denied trying to read scaling_max_freq, try cpuinfo_max_freq. – LightStruk Nov 7 '14 at 16:29

indicator-cpufreq-selector is a nice little indicator tool which shows your current cpu frequency. You can even select the desired cpu frequency.

enter image description here

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You can install it using sudo apt-get install indicator-cpufreq. – Wilf Feb 26 '14 at 23:00
And after installing, you'll need to reboot before it will show up. – talyric Mar 30 '15 at 19:39

I would just like to add i7z to this list. Contrary to the other options, this works better for CPUs in the i7, i5 and i3 series that have TurboBoost.

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In a terminal, enter:

cat /proc/cpuinfo | grep name

It should display the exact model of your CPU.

This Wikipedia page on the Sempron will give you detailed specifications.

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I wanted to share this as a comment, but dont have many reputations on askubuntu, People who want to use indicator-cpufreq do not need to reboot the computer. Resetting the current X session is enough to display the icon.

sudo apt-get install indicator-cpufreq   
DISPLAY=:0 compiz --replace

You can validate the Performance and Powersave option by seeing the current frequency by

watch -d "cat /proc/cpuinfo | grep -i Mhz"

As soon as you click on a lower frequency / Powersave, the powermanagement of the CPU kicks in, thereby reducing the clock cycle.

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