The 4x16GB 3200MHz RAM will work at 3200MHz with the Ryzen 9 5900X processor on the Asus ROG Crosshair VIII Hero (sAM4, X570) motherboard.
This is because the Ryzen 9 5900X processor officially supports up to 3200MHz DDR4 memory.
However, it is important to note that this is just the official support speed. Some Ryzen 9 5900X processors may be able to run RAM at higher speeds, but this will depend on the individual processor's memory controller. If you want to try running your RAM at a higher speed, you can enable XMP (Extreme Memory Profile) in your motherboard's BIOS.
XMP is a memory profile that is stored on the RAM modules themselves, and it contains the optimal settings for running the RAM at a higher speed.
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