A video covering dual-channel RAM upgrade options that explores that mixing RAM sticks can actually be viable, would be beneficial for many. This is an upgrade path that many may be overlooking because of misinformation.
In my old PC, I had two 4GB sticks of DDR3, and I was looking to upgrade to 16GB, and there are tons of other forum posts out there saying "don't mix different RAM sticks" and "only pairs sold together will work together properly." But with the insane price of RAM these days, it certainly wasn't a cost effective upgrade for the questionable benefit.
I managed to find on Kijiji for $30 a pair of G.Skill RAM 2GB sticks that were identical in every way to my 4GB sticks, except for the capacity. I installed them and everything works in dual channel mode without errors at all. I now have 12GB of RAM.
My kids' PC has two 4GB sticks of DDR3 and although they are from different manufacturers, they too work just fine in dual channel mode without errors.