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What processor will perform better, i5-2500K or i7-960, regarding certain FFT operations per second, for example: complex FFT in-place on 16k buffer length?
I am asking that because I would like to saturate all cores and all threads, and since i7 has 8 threads and i5 only 4, my main concern is if the SSE instructions are able to run in parallel on all 8 logical threads.
This test http://ixbtlabs.com/articles3/cpu/ci7-turbo-ht-p1.html?pages=ci7-turbo-ht-p1.html
shows that gain from turning on the HT on i7 was 0% for FFT. (Scientific applications table, line FFT). The FFT was from MATLAB ( based on a library called FFTW).
i7-960 has 4 cores and 8 threads is from HyperThreading (HT). As was shown by ixbt, HT will not help to compute more FFTs, so I recommend you to buy newer i5-2500 with same 4 cores, but greater freq, greater turbo boost (dynamic overclocking) and newer technology.
Also, this ‘i5’ is of next microarchitecture (SNB – Sandy Bridge) and it has an AVX (twice a lot FLOPS per GHz). If FFT can use it (use modern library and modern compiler), it should almost double FFT performance (if we will not consider the memory bw limits). Intel says, there is 1.8x grow from AVX in their newer MKL: http://software.intel.com/en-us/articles/intel-avx-optimization-in-intel-mkl-v103/
So, the i5-2500 is 1.8x better per tick from AVX, it has a bit more GHz (both from spec and TurboBoost) and it supports faster memory (DDR3-1066 for NHM and DDR3-1333 for i5 SND).