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What happens when i disable a core in a multi core processor?

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June 25, 2011 7:51:39 AM

hi all,

I have a multi core processor (phenom ii x4 955 BE 3.2 Ghz). I want to work in a software which does not support multi processing.

I know I can disable cores. my question is, whether disabling a core will add its resources to remaining core ( i mean if i use only one core, will my using core's speed become 3.2 x 4 =12.8?)

Please help me know it.

I am a noob in this stuff and sorry for my poor English.

Thanks,

Nishanth

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June 25, 2011 8:25:17 AM
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Disabling 1 or more cores does NOT add its resources to the remaining core(s).
a b à CPUs
June 25, 2011 9:08:06 AM

No.

In Sandy Bridge, running fewer cores allows the remaining cores to run a little bit faster. Not double the speed, but rather a few increments faster; from 3.4GHz to 3.7GHz, for example.
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June 25, 2011 9:23:55 AM

compulsivebuilder said:
No.

In Sandy Bridge, running fewer cores allows the remaining cores to run a little bit faster. Not double the speed, but rather a few increments faster; from 3.4GHz to 3.7GHz, for example.


Really? I guess that makes some sense. Is this with or without overclocking?
a b à CPUs
June 25, 2011 9:50:31 AM

Newest AMD CPUs do this to. You don't have to disable anything however, it's automatic.
a b à CPUs
June 25, 2011 9:53:45 AM

deadcells said:
Really? I guess that makes some sense. Is this with or without overclocking?


Yes. On Sandy Bridge systems you can only over-clock by adjusting the multipliers. You can adjust the base multiplier, and (sometimes) the size of the steps for the Turbo Boost.

BTW: the Turbo Boost depends mainly on temperatures. The cooler that you keep the CPU, the longer the Turbo Boost will run before it slows down.
June 25, 2011 10:59:15 AM

Best answer selected by nishanth2050.
a c 94 à CPUs
June 25, 2011 2:21:18 PM

I suspect (but don't really know) that there may be some benefit in certain applications -- but it would be very difficult to quantify.

You would simply have fewer cores sharing the L3, and this would be a boost. You might want to check something like single-thread CineMarks between PhII X2s & X4s at the same clocks.

What you essentially would be showing is that even cores at rest may have flushed enough of something into the L3 to ding performance slightly -- but it's a little misleading, as the AMD arch seems to get diminishing returns from piling on the L3.

In other words -- adding 10% more L3 gets you a 5% boost in performance; and adding 20% more L3 might get you a 7.5% increase in performance.


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