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I've just seen this comparison of two differenc CPUs.

The first one has 4.4GHz and the other one 2.5 to 3.5GHz. However, the one with the lower frequency scored better in the single-thread-rating than the one with 4.4GHz. What leads to this interesting result?

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    There are many different factors that determine performance than just clock frequency.
    – Matthew
    Oct 31, 2014 at 16:49
  • @Matthew, and which factors are that for these two CPUs?
    – MinecraftShamrock
    Oct 31, 2014 at 16:52
  • architecture, number of instructions that can run at the same time, cache size, memory bandwidth, instruction set...
    – phuclv
    Oct 31, 2014 at 16:54
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    The only thing I can find that's "worse" about the lower rated one is that it doesn't have AVX2. So probably the benchmark uses that if available.
    – harold
    Oct 31, 2014 at 16:58
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    @MarkSetchell which explains the large difference in multit-hreaded score, but not the difference for the single-threaded score
    – harold
    Oct 31, 2014 at 17:21

1 Answer 1

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You are comparing a Xeon 5698 processor (4.4 GHz) with an E3-1265 (2.5-3.5 GHz). Here are some reasons why they measured the single thread E3 performance as faster:

  • L1 caches are twice as big on the E3.
  • L2 cache is twice as big on the E3.
  • More register read ports on the E3.
  • Better branch predictor on the E3.
  • Instructions are cached after decoding on the E3.

The Xeon processor you are comparing is two families older than than the E3-1265. See this for details on how the Ivy Bridge family is faster than the Nehalem family.

(Note that it is hard to tell what exactly is causing the difference without knowing exactly what the benchmark code does.)

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