Mixing soldered RAM with a single stick hurts game performance.

Yes. You’ll take a measurable hit in games that care about memory bandwidth, which is most of them these days.

The problem is dual-channel mode. Most laptops with soldered RAM already use two channels (two memory chips on board). When you add a single socketed stick, the system usually falls back to single-channel mode because the two channels aren’t matched evenly. That effectively cuts your memory bandwidth in half.

In CPU-bound games—think Civilization, Factorio, Call of Duty, or anything that runs at high frame rates—the penalty can be 10–20% or more. You might not notice in GPU-heavy games at 4K, but in competitive shooters or sims it’s real.

The fix: either don’t add a stick (stay with soldered dual-channel) or add two socketed sticks to replace the soldered ones if your laptop lets you disable the soldered RAM. If you only have one RAM slot, you’re stuck with single-channel no matter what, and that’s just the machine’s limitation.

Check your laptop’s manual before buying. Some allow you to disable the soldered RAM, but most don’t.