There's a prevailing misconception you cannot use different RAM sizes together or that you cannot mix RAM brands. ... The answer is Yes, you can mix RAM sticks and RAM sizes and even different RAM speeds—but mixing and matching RAM modules isn't the best for system performance.

What happens if my RAM doesn't match?

In general, when the speed of several memory modules do not match, they will all run at the speed of the slowest module. Unless the system doesn't support the memory at all, the computer should function, but you may not be getting the best possible performance.

Why is it bad to mix and match RAM?

Don't even try. You cannot mix different generations of DRAM. In fact, you can't install a different generation of DRAM in your system at all. The reason is that your motherboard is built to process one generation of memory.