@wi5pa I encourage you to read this article about memory, before critiquing others and spreading misinformation:
https://www.tomshardware.com/reviews/pc-memory-ram-frequency-timings,6328.html
Firstly, having one memory module in single channel does not affect frequency in any way... by running the memory in dual channel you double the bandwidth, not the frequency.
About the frequency number is like
@SkyNetRising said... you can find it in the article:
Data Rate is the number of times per second (frequency) that a module sends and receives data. Clock signals resemble a square wave, and Double Data Rate simply means that data is transferred on both the rising and falling edge of the clock signal. Doubling the data rate in this manner allows (for example) a 1600 MHz wave to transfer data 3200 times per second. Because DDR data frequency is twice its clock frequency, it’s often referred to using the term MT/s (mega-transfers per second).
Secondly, DRAM(Dynamic Random Access Memory) is called Dynamic because of the technology it uses... definitely not because the frequency is variable. You can change it, but the motherboard won't dynamically adjust DRAM frequency, voltage and timings during normal use.
Those JEDEC profiles you see are just sets of standard frequency and timings combinations that could be used with the module. Memory can be set manually from the BIOS to those values, but they do not automatically adjust depending on load. So, DRAM voltage, frequency timings, etc. are all static (you might see very minor fluctuations in voltage... it's normal).
No need for hate and "furiously" downvoting others... it's especially rude when they're right.
Simple advice: before arguing with others make sure that you thoroughly know what you're talking about beforehand.