Single, dual and quad channel memory performance: More lanes, more speed?

New insights in the role of multichannel memory


Benchmarks applications

The synthetic test of the memory bandwidth does not surprise us. Both the Pentium and the 8-core 5960X show gigantic improvements when doubling the amount of channels. However, in most cases the performance gains are lower than the maximum possible improvement: we only see a consistent increase of 100% when writing. The increased bandwidth does translate to a near 100% performance increase for the Pentium, however the same cannot be said for the 5960X, as we only see an 80% increase here. Lastly we duplicate, or 'Copy', the memory, where we see a bandwidth increase of 80% on the Pentium and 90% on the 5960X. The effect of the slightly faster memory we used with the Pentium can also be seen clearly: the write speed of the Pentium has increased about as much as the difference between 2133 and 2400 MHz. The used platform does not seem to make a difference.

Intel Pentium G4620 Single channel Dual channel Improvement
Throughput speed      
AIDA64 Memory - Read 18,068 MB/s 35,152 MB/s 94.6%
AIDA64 Memory - Write 18,120 MB/s 36,307 MB/s 100.4%
AIDA64 Memory - Copy 17,572 MB/s 31,620 MB/s 79.9%
TechArp x264 (pass 1) 38.4 fps 40.8 fps 6.4%
TechArp x264 (pass 2) 9.0 fps 9.1 fps 1.9%
Cinebench 15 multi-threaded 397 403 1.5%
WinRAR packing 10GB 12:29 10:52 14.9%
Average     6.2%

We can now confirm that bandwidth does indeed increase tremendously when using multiple channels, however what does this mean in practice? It turns out that this is different per CPU. The x264 encoder for example is a bit faster on the Pentium when the processor uses dual channel memory. The difference in Pass 2 might be very small, however considering the consistency of this benchmark, we'd say that it will be a bit faster here. We see the same thing with the 5960X, however the differences are much smaller - so small in fact that we can't separate them from margin of error. Nevertheless it's not far-fetched to say that quad channel makes this processor a bit faster.

The Cinebench scores don't vary a lot in general based on the memory speed or bandwidth. Due to this reason it's often used as a baseline of the processor performance. However we did find a small performance increase of 1.5% with the Pentium, while there are no differences between dual and quad channel on the 5960X. There might be a difference when the bandwidth is very low and therefore gets a huge boost due to dual channel, while quad channel is a bit overkill.

Intel Core i7 5960X Dual channel Quad channel Improvement
AIDA64 Memory - Read 32,51 MB/s 57,825 MB/s 79.9%
AIDA64 Memory - Write 26,917 MB/s 54,220 MB/s 101.4%
AIDA64 Memory - Copy 28,495 MB/s 54,035 MB/s 89.6%
TechArp x264 (pass 1) 115.1 fps 116.8 fps 1.4%
TechArp x264 (pass 2) 33.1 fps 33.2 fps 0.5%
Cinebench 15 multi-threaded 1606 1605 -0.1%
WinRAR packing 10GB 2:54 2:50 2.4%
Average     1.1%

Lastly, the WinRAR test, where we pack a 10 GB file. The Pentium G4620 gets a significant performance boost: the needed time decreases from 12:29 to 10:52. This is the biggest performance increase we've seen so far out of all applications, in fact it's no less than 15%. The performance increase on the 5960X is much lower however, only 2.4%. All in all, more channels don't necessarily translate to a performance increase in the applications we've tested. The bandwidth does increase a lot, however the actual performance increase generally is not there. If there is a difference in performance, the Pentium benefits much more than the 5960X.

Also read these memory module articles on Hardware.Info

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