PCR cycle - (Oct/29/2008 )

By reducing the no of cycle what actually happen. Does the yield of PCR is decrease or non specific amplification is reduced.

depends on your application. As standard PCR is an end point analysis only, the yield can stay the same. Non specific amplification CAN be reduced but not necessarily is.
Usually the best to do is: just try

But maybe if you tell us more about your problem you can get a more precise answer.