Mixing RAM speeds: slower wins

Mixing RAM speeds: slower wins

Yes, the system will run at the lower speed (2666MHz) and the looser timings (CL16 or whatever the 2666 stick’s secondary timings are). The motherboard forces all sticks to the same settings based on the slowest stick’s JEDEC profile.

Your 8GB 2666 CL16 stick plus a 16GB 3200 CL22 stick will end up running at 2666 MHz with the 8GB stick’s timings (CL16, likely). The 3200 stick will downclock. No real compatibility issue — DDR4 is pretty forgiving — but dual‑channel mode will only work for the first 8GB (assuming the 8GB stick is single‑rank). After that, the extra 8GB on the 16GB stick runs in single‑channel. That’s fine for most tasks.

If you’re doing memory‑sensitive work, consider replacing both sticks with a matched kit. For everyday use, this will work, but you’re leaving performance on the table.