ASUS doesn't list 4 module RAM DDR4-3200 support for first generation Ryzen processors.
And for Ryzen 3000 series, officially they support these two ad DDR4-3200 speeds, and numerous others at higher speeds.
So I would suggest you either go by the QVL ists at https://www.asus.com/us/Motherboards/ROG-CROSSHAIR-VII-HERO/HelpDesk_QVL/ and/or ask on the ASUS forums.