Can I use mismatched RAM sticks, or should I match them exactly?

Yes, mismatched RAM sticks usually work, but you’ll leave performance on the table. Your motherboard runs both sticks at the slower stick’s timings, and dual-channel engages if capacities match. However, compatibility is finicky — far-apart timings or different generations can cause instability or crashes. For best results, match the exact model or at least the same brand/speed/timings.