Dual-channel vs. Single-channel, does it matter?

Dual-channel memory mode means that the memory controller on the mainboard is able to access the memory using two channels instead of one. This in theory doubles the available memory bandwidth, but in practice you will see a smaller increase in performance. Sometimes it is said that the increase in performance is neglible and some people claim 10-15% increase in performance.

However, the people who are interested in these performance gains are often running systems with a discrete graphics adapter instead of an integrated GPU. If you own a laptop or a miniature PC such as an Intel NUC you will not have a possibility to install a separate graphics adapter into your PC. The integrated graphics adapter will use system memory as its memory as well, so I was left wondering if there is a significant difference in the performance when comparing single-channel vs. dual-channel. I decided to try it out with an Core i5 Broadwell NUC, NUC5i5RYK.

Test Setup

In order to enable dual-channel mode you will need two memory modules with identical specifications (ideally two identical modules) instead of just one. Note that all NUC models do not have 2 memory slots, so they’re limited to single-channel mode. In my testing I used a single 4GB memory module for the single-channel test and then two 2GB modules of similar specifications for the dual-channel test.

I tried this out using a Windows 10 system and ran benchmarks using Cinebench R15 and 3DMark. In the single-channel setup I used a single Kingston KVR16LS11/4 module that has capacity of 4 gigabytes.

Single-channel setup

Single-channel setup

In the dual-channel setup I used two Hynix HMT325S6CFR8A modules that each had the capacity of 2 gigabytes. CPU-Z shows now that the dual-channel mode is active:

Dual-channel setup

Dual-channel setup

Results

Cinebench R15

First a single channel test that yielded OpenGL result of 23.45 fps and 261 cb for the CPU test.

NUC5i5RYK Cinebench R15 result, single-channel memory

NUC5i5RYK Cinebench R15 result, single-channel memory

A system with the same amount of memory, but dual-channel mode activated showed a nice increase – 34.81 fps for the OpenGL test whereas the CPU test did not result in any improvement.

NUC5i5RYK Cinebench R15 result with dual-channel memory

NUC5i5RYK Cinebench R15 result with dual-channel memory

3DMark

First the single-channel results.

NUC5i5RYK 3DMark results using single-channel memory

NUC5i5RYK 3DMark results using single-channel memory

And then the dual-channel results…

NUC5i5RYK 3DMark results using dual-channel memory

NUC5i5RYK 3DMark results using dual-channel memory

The 3DMark results have improved throughout. Most of the differences can be observed in the graphics tests, but the more CPU-intensive physics tests do show small improvement as well.

Conclusion

The dual-channel setup beats the single-channel setup hands down. Some benchmark results show an improvement of almost 50%, whereas the less GPU-intensive tests might show only 0-5% increase. If you plan on doing anything that’s going to stress the integrated HD Graphics adapter on the NUC, it really pays to setup your system in dual channel mode. In your average desktop use I doubt there’s any noticeable difference though.

NUC5i5RYK Benchmark results, dual-channel vs. single-channel

NUC5i5RYK Benchmark results, dual-channel vs. single-channel

Interestingly ASRock advertises the dual-channel capability of their Beebox system rather agressively as an enabler of smooth HEVC 4K playback. I’ve yet to get one for a review, but when I do, I intend to have a look if this makes a difference (their video comparison is likely off as I’m able to see great HEVC performance with single-channel Braswell, but that’s another story). HEVC 4K playback was not a factor here, as the Broadwell i5 CPU/GPU does not have HEVC decoding capabilities built into the hardware. The CPU could decode 1080p 60 frames per second in both dual-channel and single-channel setups with relative ease, but 4K resolutions were too much.

10 Responses

  1. Pawel says:

    I don’t think dual-channel setup is important in NUCs in real world scenarios. Recently I’ve bought 5MYHE, 3RYK, 3RYHx2 and PPYH. I got some 8GB 2133/11 ram sticks in these and it works really fast. I put 850s and 850EVO M.2 too.
    I’ve never heard of these benchmarks, I can only confirm to anyone: if you’re looking for a small computer for Firefox, Office, Gmail, Youtube get PPYH! Its support for h.265 via MPC-HCx64 is wonderful considering how many Watts it eats. This is all you need guys. I know it sound incredible but i3 nucs are overkill for home user. I bought it for intense data base driven office usage. Braswell is great. Oh and I installed Win 8.1×64.

    • Olli says:

      You’re correct that dual-channel does pretty much nothing when it comes to office applications. You’re also correct that Braswell does HEVC decoding better than any of the Broadwell models.

      I don’t think the i3 NUC is an overkill for desktop though. I’ve been playing with the Broadwell i5 model last few days and pretty much everything is more snappy than on the Braswell NUCs (both the Celeron and the Pentium, although obviously Pentium-model is better). It depends how much tolerance you have towards small delays (when opening a complex web page for example my Celeron Braswell might “think” a second or two before I can continue browsing and scrolling the page) – on the i5 none of this happens.

      As you have done, installing an SSD drive is a must for any system regardless of the CPU frequency.

  2. Thanks for providing such a detailed review of dual channel versus single channel, much appreciated.

  3. cs mr says:

    Very useful info, thanks!

  4. Josep A. says:

    So to get this almost 50% improvement, we can use 2 identical modules (2x4GB) or twin 2x4GB kit instead of 1x8GB. Is this correct ?

    • nucblognet says:

      Yes, that’s correct. Sometimes (rarely) two memory modules are not identical, even though they have the same product number. In such cases there’s a (small) chance that they don’t work in dual-channel mode optimally. Buying a kit eliminates this problem. Of course if you buy 2 identical modules at the same time, they’re more than likely identical…

  5. dkdkdk says:

    People decide on a whim what matters or not… Usually everything matters, unfortunately. Except for overclocking. It can’t make a bad CPU good, because it has mostly too few cores, and it’s not relevant for good CPUs because it probably has all kinds of other bottlenecks which prevent it from performing at stock as it should, and which should be enough for anything non-professional.

  6. Mark says:

    what happen if i put single channel slot 4gb and 2nd slot i put dual channel 8gb?

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