USB headers on motherboard

[Swaggernaut]

the motherboard i want which is a ASUS Crosshair V Formula 990FX only has 4 pin fan controlers but i have fans that are 3 pin fans. can i plug them in there, if not what do i plug them into

 

[Nikolay Savov]

the motherboard i want which is a ASUS Crosshair V Formula 990FX only has 4 pin fan controlers but i have fans that are 3 pin fans. can i plug them in there, if not what do i plug them into

Yes You can !
look you old 3 pin mobo conector and keep the lead pin on the 4 pin conector
In most of the motherboard the black pin is 1 pin

 

[Tradesman1]

Should be a plastic guide at the fan header that will match up to your 3 pin connector