case cooling antec fan

[n swali]

can anyone help me?
I bought the antec p160 case that included rear 120x120x25 cooling fan.I
wanted to see what the temps were like with another one fitted to the
front.I ordered one and got it but found there was a difference in
thickness.this one is 38mm thick.it would not fit in the front of the case
so i had it fitted at the rear.
it booted up fine and the temperatures went down,but now it seems to stop
and sttart every other second.is this normal? have i got the wrong one for
this case? it is made by antec as well.I would appreciate any help on this
matter.
N

 

[Matt]

it seems to stop
and sttart every other second.is this normal?

I don't know everything, but that does not sound normal.