I just built a new PC with 2x8GB of 3600MHz RAM, but I have a single 16GB RAM stick from my old PC that's probably under 3000MHz. Should I install the old RAM alongside the new one? Will there be any performance bottlenecks due to the different speeds, or should I just leave the old module out and not worry about it?
4 Answers
If you add the old RAM, it will likely downclock the speed of your new RAM to match the slower stick. So even though your new RAM is rated for 3600MHz, it'll run at around 3000MHz when paired with the old one.
It’s possible to mix RAM if they're the same type (like DDR4 or DDR3). I once combined an old 8GB DDR3 stick with a random 4GB stick, and it worked fine, albeit not at peak performance. If you already have the RAM, why not try it out? You won’t break anything.
Using that 16GB stick might cause compatibility or performance issues, so it's a bit of a gamble. What's your CPU, though? That might affect whether it's worth trying.
You could install both 8GB sticks in one channel and the 16GB in another for dual channel mode. Just don't enable XMP. It should work, but remember, the overall speed will drop to about 3000MHz, and you might experience slower timings.
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