What is the name of this kind of fan connector?

[Jasis]

Hello. I need to switch a fan, but the fan does not have a common 4-pin motherboard connector. The connector is 3-pin and much smaller, and there is a convex in the middle. What is the name of this connector and where can I find fans with this connector?

 

[Unolocogringo]

Your normal typical 3 pin fan connector.

 

[The Paladin]

What you have a an standard fan 3pin connector.
More to the question would be what does the connector on your motherboard looks like?
if unable to take a picture can you tell us make/model of the motherboard?

 

[Jasis]

OK, found it. It is 3 pin 'mini' connector.