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Old 2014-07-28, 16:35   #4
A Sunny Moo
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Aug 2007

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Ah, that would do it - I happen to know for a fact that the i5-2400 is not running in dual channel mode. (When I built it I had to pick up the RAM last-minute at a local store, and all I could get my hands on at the time was 1 4GB stick.)

The AMD, by contrast, has 8 GB of 665 MHz memory - not very fast, but it is running in dual channel mode (2x4 GB), as confirmed by CPU-Z.

That makes a whole lot of sense - thanks! I'll have to look into putting a second module in that i5...

Also, thanks George for the tidbit on FFT sizes - I forgot the need to multiply by 8. In that case, then, seems that both machines are operating out of cache for the 448K FFT, which would explain the memory bandwidth issues. The 96K FFT, by contrast, is well within the Intel's 6 MB L3 cache, but outside the AMD's 512 KBx4 L2 cache, which is why the Intel does so much better there.

Last fiddled with by mdettweiler on 2014-07-28 at 16:38
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