Can a Ryzen 5 3600 and B450 motherboard run mixed 3000MHz and 3200MHz RAM at 3200?

You can try enabling the memory profile in the BIOS and manually testing 3200MHz, but be prepared to reset the settings if the system fails to boot. Run a proper memory stability test afterward instead of assuming it is fine because Windows starts.

Mixed memory usually runs at the speed and settings shared by both modules, often defaulting to the slower stick. The modules might work together at 3000MHz, but reaching 3200MHz depends on the memory chips, timings, voltage, and the motherboard’s memory controller.

There’s no guaranteed CPU or motherboard combination that will make mismatched memory run at 3200MHz. The 3000MHz module would be running above its rated speed, so this becomes an overclocking attempt and may not be stable.

The most reliable option is to replace the mismatched modules with a matched 2x16GB kit, ideally one rated for 3200MHz. Using identical sticks reduces the chance of crashes, boot problems, and random instability. Even with a matched kit, enabling the memory profile is technically an overclock and should be tested.

Some systems can run four or mixed sticks at 3200MHz without trouble, so it isn’t impossible. However, another person’s stable result doesn’t guarantee the same outcome for these two different modules; the exact memory chips and timings matter.