memory chip?

Memory chip you mean RAM , if so RAMs have compatibility with certain motherboards RAMs are DDR 1 2 3 4 5 , and every ram in the range will only suit on it motherboard , you can read the motherboard features to understand which memory supports on it , the memory socket is not suited with it structure also , to prevent the memory from damaging if one try to install incompatible one , memory chips are built by certain companies like Hynix Transcend Kingston Corsair and they only build ram , others don't try like Logitech or samsung or I ball because these Ram brands have a reputation for many years , and when you upgrade ram the clock speed of Ram in hz have a role in the speed and price

The ram modules must match the speed and density that the motherboard supports.

Go to any memory vendor website and it will tell you which specs ram you can use.

For example:

http://www.kingston.com/us/memory/system_specific/...

Manufacturer doesn't matter. But there are other details that do matter. If you have a computer right now that you want to upgrade its RAM, tell us the computers' make and model and hopefully I can tell you what details are important for that computer.