We test DDR4 memory with a ASUS Maximus VIII Impact motherboard and an Intel Core i7 6700K processor. The clock speed and uncore of the processor were both at 4.0 GHz, with turbo mode turned off.
We bench the modules as follows: firstly, we run all of our benchmarks using XMP settings. After that, we determine the maximum achievable speed using XMP timings and voltages. We use the memory multipliers to overclock the sticks. After that we determine the maximum overclock using XMP timings and an increased voltage. Lastly, we also test how far we could overclock these sticks while freely adjusting the timings and voltages.
Overclocking the memory does not make such a difference in performance of already fast modules. Still, there are overclocking hobbyists who do just that.