3pin vent splitter

Ady20

Honorable
Jan 24, 2013
38
0
10,530
So I have a 120mm vent at the front of the PC, and 1 80mm vent that takes the air out. I only have 1 3pin connector on my MB.
I found in my box of "goodies" a 3pin splitter. 1 end has 3 cables(yellow, red, black) and the other end only 2(red,black).
My question is witch vent to connect on witch end. If I connect a vent on the 2 cable end only it won't work at max capacity? Because red is 5v and yellow is 12v...or something like that? Excuse the dumb question but I'm not a pro.

And thank you a lot for the upcoming replies.