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I am running a Intel Core i7-4820K on a ASUS Rampage IV Extreme Motherboard, my OS is Windows 7. It has 4 physical cores (8 logical). It supports several operations points from 1200 MHz up to 5700 MHz.

When I take a look at the current speed in HWINFO74, it only shows 1 core (core#0). This core seems to run on the lowest frequency (1200 MHz) all the time, even when I start CPU heavy benchmarking tools.

I also ran the Windows Experience Index, the processor only score 3,8 out of 7,9 possible points, which seems strange as well for such a modern CPU.

What could cause this issue and what should I do to investigate further.

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    On the ASUS support website there are a lot of BIOS updates which mention support for new CPUs, so you might need to update your BIOS for the CPU to run as expected. – Gene Nov 18 '13 at 7:41
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    @Gene A BIOS update did the trick! Please add this as an answer and I will accept it. Thanks for all the other hints so far, I tried them as well but in vain. – Demento Nov 18 '13 at 18:11
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As your CPU is two generations newer than those the ASUS Rampage IV Extreme was originally meant to run with, you might need to update your BIOS to allow the board to properly detect your CPU. The ASUS website shows a lot of BIOS updates adding support for new CPUs.

  • Thanks, this actually solved the problem and all cores are available and used now. – Demento Nov 20 '13 at 11:37
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Have a look around your BIOS. It's possible that for some reason it's come under-clocked. This would not be a default setting, so you could just restore default settings and reboot.

Failing that, you'll have to understand your BIOS settings that relate to over clocking / performance and confirm that they are not causing this problem. From the BIOS, it is (usually) possible to both underclock and limit the number of cores available to the OS - have a look around and read your motherboard manual. I would also recommend reading at least one online tutorial on overclocking i7

You could also check it's not Windows doing this (I think unlikely) by booting onto a linux live CD and checking from Linux. Once booted, open a terminal and run cat /proc/cpuinfo and have a read of the output.

As a final point, with such a powerful and comprehensive CPU / MB, I would recommend learning every configuration option in your BIOS - this will enable you to get the most out of your hardware and use it to it's full potential (as well as debug issues like this)

Hope this helps,

Will

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If power settings are set to "Power saver" specifically the "System cooling policy" being on Passive, the processor will stay stepped down on my system for quite some time. Eventually when work is being thrown at it over and over again, it will speed up.

Power Profile

If somehow the maximum processor state was set lower than 100% (not a default state), it will also effect processor stepping.

These are very interesting ways to force these new systems to stay in a low state, based only the power policy of the OS (and the hardware working with it).

Asus motherboards also have software for the hardware that will set different modes to do very much the same thing. Like the asus Suite software.

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