Mixing RAM sizes usually hurts performance.

No, it won’t help — and it might actually slow things down.

Here’s the deal: Your soldered 16GB is already running in single-channel mode if it’s a single stick. Adding an 8GB stick in the other slot will either keep everything in single-channel (if the system forces it) or run in “flex mode” — where 8GB from each stick talks dual-channel, and the remaining