You didn't read Menthols response. I think the most important take away is that Fans have 2 ratings. Amp rating and startup Amp rating. For instance a fan could have a .2a rating but could use .6a when powering up, not good when 2 or more fans are connected! You might be ok but would you want to ruin your motherboard cause of a stupid burnt fan header? I wouldnt.
I use 2 swiftech PWM sata fan hubs (one for each rad), they are small and can support up to 8 fans and take power from the psu. Best $10 investments I ever made!
I'm sure the 3A header could support 3 fans no problem
Btw the swiftech fan hubs connect to the back of the case so they are not visible
ASUS Maximus 13 Hero, Intel I9 11900k, EVGA GeForce RTX 3080 FTW3 ULTRA