The single-channel penalty is overblown

Yes, you lose some memory bandwidth when soldered RAM is paired with a single socketed stick, but for most people the difference is a rounding error.

Here’s the deal: if your laptop has 8GB soldered and you add one 8GB stick, they almost certainly run in single-channel mode because the two channels aren’t balanced. The soldered module uses one channel, the socketed stick uses the other—but they’re not a matched pair, so the system defaults to single-channel. Same thing happens if you mix capacities.

The real-world penalty depends on what you do. Basic office work, web browsing, streaming? You’ll never notice. Even light gaming usually sees a 5-10% frame rate drop at most. The big hit comes in tasks that hammer memory bandwidth: video editing, large spreadsheets, compiling