Yes, you can use a 3000MHz RAM stick with a 3200MHz RAM in dual-channel configuration.
Yes, you can use a 3000MHz RAM stick with a 3200MHz RAM in dual-channel configuration.
You have Corsair Vengeance 8GB RAM at 3200MHz, currently using it at 3200MHz. You're considering a 8GB Corsair Vengeance 3200MHz stick. Your existing 3000MHz RAM is already running at 3200MHz, which means it's in dual-channel mode. The new RAM should work seamlessly with your system.
They’ll both settle on 3000 Mhz once you install that second stick. The compatible settings will match the narrowest range of the two. Later, you can attempt to raise them both to 3200 Mhz and it should work if your system remains stable with just one stick.