Mismatched RAM sticks usually work, but you'll leave performance on the table.

Yes, it will probably work. Your motherboard will run both sticks at the timings of the slower one, and dual-channel will still engage as long as the capacities match. So you’ll get 16GB in dual-channel, which is a big upgrade from 8GB single-channel.

But “probably” is doing a lot of work here. RAM compatibility is finicky. If the timings are really far apart or the sticks are from different generations, you might get instability, random crashes, or the board refusing to boot. Your best bet is to match the exact model or at least the same brand/speed/timings as your existing stick.

Performance loss is small but real. Because both sticks run at the slower stick’s timings, you lose the tighter timings of the faster one. In gaming and everyday tasks, you won’t notice. In memory-sensitive workloads like video editing or compiling, it might cost you 5–10%. Annoying, but not the end of the world.

If you can, spend the extra few bucks to match the stick exactly. Your motherboard will thank you, and Future You won’t have to troubleshoot random blue screens.