I checked on the motherboard's website and it only mentions the "PRO 2700X", but on their x470 motherboard it has both the "PRO 2700x" and the "2700x"
b450: https://www.msi.com/Motherboard/support/B450-TOMAHAWK-MAX#support-cpu
x470: https://www.msi.com/Motherboard/support/X470-GAMING-PRO-CARBON#support-cpu
b450: https://www.msi.com/Motherboard/support/B450-TOMAHAWK-MAX#support-cpu
x470: https://www.msi.com/Motherboard/support/X470-GAMING-PRO-CARBON#support-cpu