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AMD FX 4100: Disable 2 cores?

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  • CPUs
  • Performance
  • Processors
  • AMD
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December 27, 2012 8:12:12 PM

So this morning I decided to try disabling a couple of cores on my fx 4100 which is currently also overclocked to 4.2ghz. Ive noticed an odd speed increase in just the general feel of windows. It feels much faster over all which is really weird, One would think that the processor would be faster with all its cores enabled but right now its the complete opposite. I remember a while back when this processor released a few tech blogs saying that disabling a core or to would help performance is this true? have I actually done some good and improved performance? Or should I re enable the other cores?

More about : amd 4100 disable cores

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December 27, 2012 8:42:15 PM

It depends on what youre doing I would imagine. if you disable 1 core in each BD module that would leave with with 2 full cores instead of 4 sudo cores where 2 cores fight for shared resources. Thats what happens you see, cores 0 & 1 share somoe resources so when a multithreaded app runs on them one has to wait for the other to finish before it cvan use the resources and sometimes this can have a detrimental effect on processing. Intels Hyperthreading can sometime have the same negative impact on a program but at least with intel, HT is easy to shut off..
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December 27, 2012 8:42:31 PM

Might be a placebo effect :-)

Having some core disabled might allow the CPU to reach a slightly higher clock speed on the remaining cores, which would help single threaded apps. In other words maybe your system is being thermally throttled at the moment.

I don't think this would translate into a large noticeable difference in the feel of Windows. The thing that makes Windows feel slow isn't normally the CPU, it is the disk being used and if you have enough RAM for caching of the disk.

Disabling cores would really hurt applications that are well threaded however. I can't imagine how it could be an overall benefit.



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December 27, 2012 8:51:43 PM

Hers some bench mark first one is with 2 cores/threads disabled ,2nd image is with no cores disabled.


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December 27, 2012 10:51:44 PM

The FX 4100 only has 2 cores. It'd be like a PentiumG series CPU vs an i3 if you disabled 2 threads.
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December 27, 2012 11:15:53 PM

The effect the OP refers to is a 15% IPC increase that occurs if the second integer core on the module was deactivated.

For example, take the 8150. Disable the second integer core on all modules. The remaining 4 cores will all be around 15% faster per clock cycle because they are no longer sharing resources.

This doesn't result in a faster processor overall. But it does produce faster single to four core performance. Not sure if its something you would feel though.

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December 30, 2012 7:39:57 PM

Falcon, my understanding is that the scheduler in Windows was already patched to remove the issue you are referring to. The details of the patch are here,
http://support.microsoft.com/kb/2645594

Most Win7 machines and all Win8 machines now have this patch installed. So I think there is zero reason to disable the cores.

I stand by my initial guess that is is a a placebo effect.
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December 31, 2012 2:11:42 AM

PassMark said:
Falcon, my understanding is that the scheduler in Windows was already patched to remove the issue you are referring to. The details of the patch are here,
http://support.microsoft.com/kb/2645594

Most Win7 machines and all Win8 machines now have this patch installed. So I think there is zero reason to disable the cores.

I stand by my initial guess that is is a a placebo effect.


The patches did very little. Manually shutting the second core down increases ipc by 15% The patches did very little in terms of speed increase. At least the stuff in the field so far.

I didn't say to disable cores. The chip overall is faster with everything active, but it does improve IPC to have the second core turned off.

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