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Why is my Calculated CPU Clock Speed Incorrect?

There are a few reasons why your calculated CPU clock speed may differ from what is expected:
  1. CPUs made for portable computers can decrease their clock speed to lower power usage. For example, a Pentium III 1000 Mobile CPU may be measured as having a clock speed of 730Mhz at the time the measurement is done.
  2. Newer CPUs also have a feature where they may over-clock some of their cores when others aren't in use.
  3. The speed rating values that AMD assign to their Athlon CPU's do not correspond to their clock speed. For example, a Athlon 2000+ runs at a clock speed of 1660Mhz. This is also the case for the older Cyrix 150+ & 200+ CPUs

For reasons 1 and 2 we are constantly endeavouring to better detect when this is the case and use other methods to find the correct speed. We believe we can do this in most case with recent versions of PerformanceTest.

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