Yes, they require power connections.
Yes, they require power connections.
You're getting the MSI B450 Tomahawk and wondering if those small cables are necessary. They likely won't require a plug-in unless you're connecting peripherals or expansion cards. Double-check your setup to avoid extra steps. You're doing great upgrading!
You already had a working PC and swapped out the motherboard, possibly the CPU. You can leave everything plugged in if you prefer. All connections are on the front side—USB ports, audio, power button (this one might matter), power/HDD indicators, or an internal fan.
Occasionally they get marked on the board. Other times they remain unmarked.
It's worth noting that not everyone reads the labels correctly—some understand their meaning while others may not.