Mixing dual-rank and single-rank RAM is usually fine.

Yes, there’s a performance difference, but in most real-world use you won’t notice it.

Here’s the deal: dual-rank RAM has more banks of memory chips, which lets the memory controller juggle data better and can give a small speed boost in certain workloads (like video editing or heavy multitasking). Single-rank is simpler and often slightly cheaper. When you pair a dual-rank stick with a soldered single-rank stick in a laptop, the system will typically run in “flex mode”—part of the memory runs in dual-channel, part in single-channel. The rank difference might also cause the memory controller to loosen timings or drop the speed a notch, but modern laptops handle this gracefully.

For everyday tasks (browsing, Office, streaming) you’ll see zero difference. For memory