We show taking into account realistic component parameters, the performance analysis of Diversity-combined Asymmetrically Clipped OFDM technique in intensity modulated and direct detected (IM/DD) passive optical network (PON) fiber link. The Diversity-Combined ACO-OFDM is shown to give better BER performance than conventional ACO-OFDM. Data rate of 13.2Gbps can be transmitted using 4-QAM/D-C ACO-OFDM through 60km unamplified IM/DD fiber link with split ratio of 128 users and 3dBm DFB-Laser. Throughput gain of 2.8Gbps is achieved when using the diversity-combining method. The BER performance value is fixed to 10^-3 (limit value when Forward Error Codes are used).