Should I replace my 2x4GB RAM with 2x8GB or add more 4GB sticks?

Replace, don’t add. Adding two more 4GB sticks risks instability from mismatched timings or voltages, even with the same model. A fresh 2x8GB kit guarantees dual-channel performance, frees up slots for a future 32GB upgrade, and costs under $20 more after selling your old kit. Don’t sacrifice stability for a few extra gigs.