Increasing the number of simultaneous users is one of the challenging issues in incoherent and asynchronous optical CDMA systems. One solution is to increase the value of cross- correlation, λc. In [3] neglecting the effect of noise, optimum value of λcwas obtained. In this work, with considering noise, the simultaneous effect of λc and transmitted power on the probability of bit error (pbe) is investigated. Our investigation is performed by employing OOC (λc =1) and prime code (λc =2) and active correlator is chosen for its robustness against the noise. The performance is analyzed for three common receiver structures, namely soft receiver (without optical hard limiter), single optical hard limiter (SHL) and double optical hard limiters (DHL). Our results show that under the same bandwidth efficiency, increasing λc in high power regimes decreases the pbe but increasing λc in low power regimes will increase pbe.