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How do you calculate the clock cycles a cpu can deliver (include Turbo Boost)? I need to replace a server CPU by a new CPU (with lesser cores, due to license costs). So I want to be sure the new CPU delivers as many (or more) clock cycles as the current CPU. Normally you would calculate socket * cores * clockrate. eg for the Intel® Xeon® Processor E5-2687W v4 that would be: 2 * 12 * 3000 = 72000.

But some people say I have to take Turbo Boost into account. They say I need to use following formula: 2*8*3000 + 2*4*3500 = 76800 others say I need to use: 2 * 12 * 3000 + 2 * 12 * 200 = 76800 They are not able to explain to me why they use one of those formulas.

Can anyone help me out and try to explain why they use the calculations mentioned above?

Thx

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    Clock cycles are not always the best metric to use. Due to lengthening instruction pipes, better handling of instruction parallelism and more processing cores (integer, SSE, FP) within the processor a newer processor could achieve more than an older core even when running at a lower clock rate. I'm not sure of any situation when knowing the "clock cycles" would give you a reliable way to compare processors.
    – Mokubai ♦
    Commented Jan 27, 2017 at 7:53
  • I only use it as an indication. The cpu's are needed for a SQL Server
    – Frederik Vanderhaegen
    Commented Jan 27, 2017 at 8:25
  • Do all your calculations based of the base frequency. Once you have all your results calculated multiple each result by (1.05) for example. This allows you to calculate the increase when the CPU boosts itself to a +5% boost frequency.
    – Ramhound
    Commented Jan 27, 2017 at 14:48
  • Your CPU has a 3.50GHz maximum boost frequency. This means has a maximum of a 16.67% frequency. For the purposes of your question, I would just calculate the following adjustments (1.05,1.10,1.16), that is more then enough data to make a decision.
    – Ramhound
    Commented Jan 27, 2017 at 14:50
  • "Can anyone help me out and try to explain why they use the calculations mentioned above?" - Since I believe your formula is wrong, I can't explain the formula you want to use, since I believe it to be flawed.
    – Ramhound
    Commented Jan 27, 2017 at 14:53

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Yes, you need to account for turbo boost. Beyond that, the actual Turbo boost ratios on all recent CPUs depend on the number of active cores (more active cores implies a lower max turbo), so you can't just multiply the cores by the max turbo ratios.

Unfortunately, Intel doesn't seem to advertise the turbo ratios on ARK, and I couldn't find it in the data sheet either. You can get this info directly from the CPU, eg with turbostat --debug 1 1, but that doesn't help you much if you don't have a copy yourself.

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