Mixing RAM sticks usually works fine.

Usually, yes. You can mix a 16GB stick with another 16GB stick to get 32GB, and it will work in most cases. Matched sets are better because the sticks are tested together for stability, but the difference is rarely noticeable for everyday use.

The risk with mixing two different sticks (even same brand/speed) is that they might not play well together. Your motherboard will usually slow both down to match the slower stick’s speed and timings, so you lose a tiny bit of performance. Worst case, you get random crashes or the system won’t boot. For gaming, video editing, or heavy multitasking, a mismatched pair can cause subtle instability that’s hard to diagnose.

If you already own one stick and just need more RAM, try the cheap route first — buy another stick with the same specs (DDR4 vs DDR5, speed, timings if you can find them). If it works, great. If you get crashes, return it and buy a matched kit. Your motherboard manual will say something scary about mixing sticks, but real-world compatibility is usually forgiving.

This is one of those places where you can save a few bucks if you’re willing to test it. Future You will either be fine or mildly annoyed.