DDR4-2400 CL15 beats DDR4-2666 CL19 in real use.

Yes, go with the used 2x8GB 2400 CL15 kit. It’s not only more capacity — it’s actually faster in latency.

Here’s the trick: RAM speed isn’t just the frequency number. Timings matter more than people think. Your current 2666 CL19 has a true latency of about 14.25 nanoseconds. The 2400 CL15 calculates to 12.5 nanoseconds. So the “slower” kit responds faster to each request. That means real-world performance will be slightly better, not worse. And you’re doubling your capacity from 8GB to 16GB, which is a massive win for multitasking.

The only catch: don’t mix the kits. Use the 2x8GB sticks alone, not combined with your old ones. Mixing speeds forces everything to the slowest common denominator, and you’ll lose the latency advantage.

Your desktop will thank you.