Agner`s CPU blog

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New CPUID manipulation program
Author: Agner Fog Date: 2010-01-22 03:54
It it possible to manipulate the CPUID in VIA Nano processors. This feature is currently undocumented, and it is different from the method described in manuals for earlier VIA processors. I have got the necessary information now, and I have made a little program that can change the CPUID vendor string, family and model number on a VIA Nano processor.

You can download the program from www.agner.org/optimize/cpuidfake.zip. It is open source (GPL). Please read the included instructions.

The program requires a VIA Nano processor, and Windows (32 or 64 bit). This program makes it possible to test if a benchmark result depends on the CPUID vendor string. You can also test if the performance of other CPU-intensive programs perform differently depending on the CPUID.

If you find any benchmark or other generally used CPU-intensive program that appears to have an unfair CPU dispatching then please let me know. You may also contact the producer of the program and ask if it has been built with an Intel compiler or Intel function libraries. It is important to know how widespread this problem is.

 
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