Can I use different sizes of RAM sticks?

Question

Iron

I'm going to buy a new laptop with 8 GB RAM. I have 1 stick of 4 GB left from the previous one. The new laptop has DDR3 1600 MHz, and mine also has DDR3 1600 MHz. I read that you can only have the same ones, for example, 4x4 8x8 ... Will everything work properly if you connect 8 and 4 GB? If you need AMD A6 7310 percent.
Thanks for the answers.

Answer 1

can

Answer 2

Naturally, it will work, but on the condition that the laptop physically supports more than 8GB and that it is physically possible to put a second bar into it.

Answer 3

identical frames are set for the Multi-channel memory architecture , then not only the volume, but also the speed is added, i.e. memory works 2 times faster (or more if supported by the memory controller).