How will DDR4 RAM work with different memory capacities (4+8? 4+4+8+8)?

Question

Iron

Tell me how the RAM will work with different amounts of memory?

1 Let's say 4GB in one slot and 8GB in another - will the dual-channel speed suffer, or rather, will the speed of 8GB sticks be equated to 4GB sticks, or will they work with one, common, synchronized into one whole, or how else to say speed and use their common 12 GB memory?
2 If one pair is a dual-channel 4+4 GB, and the second pair is a dual-channel 8+8 GB, will the speed of 8+8GB be cut?

Here I had 2 + 1 GB in two channels in my laptop. I threw out 1 GB and installed 8 GB. Total came out 10 GB of RAM. Does a two-gig stick pull an eight-gig stick to the bottom?

Answer 1

I bought myself a HiperX Predator 3200 8gb - it worked, but not right away. I inserted them in turn, swapped them, put both on a single channel. I don’t remember at what combination, but both started. Both work at 3200, with timings 16 18 18 36.

Answer 2

Case 1: the first 8 GB work in dual channel, the remaining 4 - in single channel (roughly speaking). It's called flex mode.
Case 2: a smaller volume of a kit will not affect the performance of another kit, plugged into paired connectors naturally.
With laptop: 2+8 is much better than just 8, but 8+8 is much better than 2+8

Answer 3

Let's say 4GB in one slot and 8GB in another - will the dual channel speed suffer?

It will work in single channel mode.

rather, will the speed of 8GB sticks be equated to 4GB sticks

Each bar will work with its own parameters (timings), if the frequencies are the same, then everything is ok, and if they are different, the 2nd one, which has a higher frequency, will work at a lower one.
PS If you want a dual-channel mode, be sure to have the same dimensions of the memory sticks. But the increase is insignificant, although it is always more pleasing to the soul that "I have a two-channel mode" :)
I will not answer the second question.

Here I had 2 + 1 GB in two channels in my laptop. I threw out 1 GB and installed 8 GB. Total came out 10 GB of RAM. Does a two-gig stick pull an eight-gig stick to the bottom?

You have a single-channel mode.
Install the free program CPU-Z on the Memory tab, see the mode

Answer 4

The dual-channel mode works only with the same RAM boards and the same volume.

Answer 5

Same size, yes.
Same fees? What is meant? Boards from the same manufacturer? If so, then this is not at all necessary, sometimes even boards with different frequencies plow with each other, not like boards with the same frequencies from different manufacturers.
The same applies, for example, to situations when part of the RAM (laptop) is sewn into the laptop and there is an empty socket for the board. Finding what they sewed there is almost impossible. Expand the memory by adding the same volume in the dual? Maybe not on the first try, but it will definitely work.