How to run OpenFOAM on overclocked CPU?

Konstant1n · April 5, 2023, 00:22

Hello! I`m trying to run OpenFOAM simulation on Intel core I9-9980XE overclocked by 4.8 GHz, but it runs only 3.8 GHz. There no throttling, temperatures are low.
To run simulation I use this line:
mpirun -np 16 rhoPimpleFoam -parallel
What should I do to increase CPU frequency?

vatavuk · April 7, 2023, 08:36

Hi Konstantin,
We worry about the number of cores and frequency of the processors, but the experts say that what normally limits the performance of computers is the communication between the processors and RAM memory. People say that a dual channel system works well with up to about 4 cores. A four channel system like yours should work well with up to 8 cores. Using more cores won’t make the system faster because the processors will have to wait for the information to be retrieved from memory.
If you are worried about the performance of your system, you can run the motorbike benchmark and compare the results with the ones reported in this thread:
OpenFOAM benchmarks on various hardware

April 5, 2023, 00:22	How to run OpenFOAM on overclocked CPU?	#1
Konstant1n New Member Konstantin Lebeda Join Date: Apr 2023 Posts: 2 Rep Power: 0	Hello! I`m trying to run OpenFOAM simulation on Intel core I9-9980XE overclocked by 4.8 GHz, but it runs only 3.8 GHz. There no throttling, temperatures are low. To run simulation I use this line: mpirun -np 16 rhoPimpleFoam -parallel What should I do to increase CPU frequency?

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April 7, 2023, 08:36		#2
vatavuk Senior Member Paulo Vatavuk Join Date: Mar 2009 Location: Campinas, Brasil Posts: 200 Rep Power: 18	Hi Konstantin, We worry about the number of cores and frequency of the processors, but the experts say that what normally limits the performance of computers is the communication between the processors and RAM memory. People say that a dual channel system works well with up to about 4 cores. A four channel system like yours should work well with up to 8 cores. Using more cores won’t make the system faster because the processors will have to wait for the information to be retrieved from memory. If you are worried about the performance of your system, you can run the motorbike benchmark and compare the results with the ones reported in this thread: OpenFOAM benchmarks on various hardware