Your soldered RAM is the spec sheet.

Yes — check the soldered module’s specs using free software, then buy a socketed stick that matches exactly.

CPU-Z or HWiNFO64 will tell you everything: DDR4 vs DDR5, speed (like 3200 MHz), and timings. Voltage is generally handled automatically by the motherboard, so don’t worry about that. The soldered RAM is the baseline — the additional slot will run at whatever the soldered part runs at. If you put in a faster stick, it’ll just downclock to match. If you put in a slower one, the whole system might run slower or just not boot.

Don’t rely on the laptop model number alone. The same model can ship with different RAM configurations. Open the case, look at the label on the socketed stick if there is one, or run the software first. Then buy the exact same spec.

Laptops with a mix of soldered and socketed are common in thinner models. You usually get one upgradable slot. Use it wisely.

Future You will thank you for checking before buying.