You're probably stuck with what you've got.

If your laptop has partial soldered RAM, you’re limited to one free slot, and even then you need to match the soldered module’s specs exactly—speed, latency, voltage. Mixing mismatched sticks causes crashes or the system to run at the slowest common speed.

The biggest pitfalls: buying the wrong generation (DDR4 vs DDR5), not seating the module fully (it needs a firm click), and assuming the BIOS will just figure it out. It won’t. Check your laptop’s exact supported RAM config from the manufacturer, not from a third-party site. Some laptops also lock you into specific modules via whitelisting.

Also: many modern ultrabooks design the slot to be nearly impossible to access without a pry tool and a prayer. You might break clips or the motherboard trace. I’ve seen it happen.

If you’re not absolutely sure about compatibility, consider whether the performance gain is worth the risk. Often it’s not.