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How does a higher clockspeed increase performance?

Last response: in CPUs
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November 26, 2012 11:05:00 AM

I would like to ask how does a higher clockspeed increase performance? (or does it even improve performance)

-ecoli

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Prebuilt Dell XPS8500
-GT640 Graphics Card
-Intel i7 3770 8 CPUs
-PSU 450W
a c 471 à CPUs
November 26, 2012 1:49:17 PM

CPUs are designed to execute instructions per clock cycle (IPC). The IPC is based on how the CPU architecture was designed. At the moment Intel CPUs can process more instructions per clock cycle than AMD CPUs. So AMD CPUs must be clocked higher in order to equal the performance of Intel CPUs.

If a CPU can process 4 instructions every 1Hz, then it has a IPC of 4. If the CPU is clocked at 2.0GHz, that means 8 million instructions can be executed. If the CPU was clocked at 2.4GHz then it can process 9.6 million instructions within the same time frame.

If another CPU only has a IPC of 3 then in order for it to be able to process 8 million instructions within the same time frame as the above CPU, it would need to be clocked at 2.67GHz.
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November 26, 2012 1:59:23 PM

What would the IPC or, say, on i7 3770K be? Or do all Intel CPUs have the same IPC?
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a c 471 à CPUs
November 26, 2012 2:12:13 PM

All Intel and AMD CPUs of the same "family" or architecture will have the same IPC.

Therefore, all Intel Ivy Bridge CPU will have the same IPC and all AMD PileDriver CPUs. The difference would be the number of cores. Each core is theoretically capable of processing the same # of IPC, but due to many inefficiencies, like program design, limited resources within the CPU, out of order processing, waiting for other instructions to execute and other things mean that you can not double, triple, quadruple, etc. the more cores you add to a CPU.

Of course what I have stated above is a very simplified layman's explanation.
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a b à CPUs
November 26, 2012 6:01:10 PM

There are two components to how fast a CPU can process instructions:

The first is clockspeed. The higher the clock, the more cycles the CPU runs, allowing the CPU to do more work.

The second is Instructions Per Cycle. This is a measure of how many instructions the CPU is doing per clock.
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