Could I install the new RAM myself?

RAM installation very simple. I've done it numerous times. Lots on youtube. Just follow instructions. You do have four memory slots with that MB so you can duplicate what you have and double the RAM. But you might be able to add two new 16 GB modules along with your existing memory (I'm not sure). I suggest you visit a good computer shop and ask them what your best options are for memory expansion. Or maybe someone hear whose more knowledgeable can advise.

Your four slots are divided into two sets of two.

The pair within a set should match each other.

The sets themselves do not have to match however.

So you should buy a matching pair for your second set, but you do not have to worry about matching the first set.

Try not to mix up which ones go in which set. There is more to a matching set than just being the same size. There are also internal timings that should match up.

i've tried. thanks blatham.

RAM is the easiest component to install ever, did you make it?

Thank you for sharing!

No, it's not difficult at all.

Looking at the specs for your motherboard, it supports up to 64GB of RAM. From your OP, you have two free slots to install another two sticks of RAM. So yes, you could install more RAM.

As said above, while each pair in a set should match, the two sets can be different as long as it's the same type of RAM (in this case DDR4 2666/2400/2133 MHz memory modules).

While I don't have the same motherboard as you in my current desktop machine; I do have two different speeds installed being two DDR3 1333MHz and two DDR3 1666MHz RAM modules. The board simply just defaults to the lowest speed (in this case 1333MHz) for both sets - as it says in the motherboard manual if you have RAM modules of different speeds installed. Which in my case since the board only supports up 1333Mhz RAM speeds, then it's still operating at maximum speed the board can support anyway.

https://www.gigabyte.com/au/Motherboard/B365-HD3-rev-10/sp#sp

Thanks for your recommendations and explanations!
I've never tried doing it on my own but thanks to your replies I managed to replace RAM on my own