All in all, more bandwidth does not automatically mean better performance. An increase of nearly 100 percent of the bandwidth only leads to small or non-existent performance improvements in most cases. This heavily depends on the purpose of the application and the system itself.
First of all it's clear that the Intel Pentium G4620 benefits a lot more from larger bandwidth than the Intel Core i7 5960X. This could be due to multiple reasons. The Pentium is of course a much weaker processor, and we've seen in the past that the memory speed can play a much larger role when you're CPU-bound. It's also possible that the much smaller cache is a bottleneck. The Pentium only has 3 MB of cache, compared to 20 MB on the 5960X. If the cache is smaller the processor will more easily be forced to get its data from the memory, which makes the speed thereof all the more important. Lastly, it's also possible that we're dealing with diminishing returns: the step up from single to dual channel offers significant performance improvements, however the same cannot be said for the step up to quad channel. It's not for nothing that AMD has opted for dual channel with their new Zen generation, which makes the processors less confusing and the motherboards cheaper.
In games, there is a significant performance improvement when using the IGP. This is not so weird: an IGP does not feature its own video memory and has to use the system memory for it. This is not the case with the GTX 1060. It's also possible that this card is simply not fast enough to keep up with an overclocked Core i7 5960X. The results might have been very different with a faster graphics card, since the chance of the CPU being the bottleneck is greater in that scenario.
Generally speaking, if you have an upgradable desktop PC, you'd upgrade your GPU, rather than your memory if you want to get better performance in games. This isn't always possible with laptops and compact desktops, while exactly these product groups are provide with only a single memory module by manufacturers - even though the platform in use can easily run dual channel. In practice this means you not get all the performance you could get. Reason enough to research whether a laptop supports dual channel, or to install an extra module if you have the option.