Due to the rapid development of our life toward a life with high-quality communication systems, which require large data rates for transfer such as Long Term Evolution (LTE), Worldwide Interoperability for Microwave Access(WiMAX), and Wireless Fidelity (WiFi) which use Multiple Input - Multiple Output (MIMO) systems. Therefore, become necessary to interest in MIMO system parts especially the MIMO detector (MIMOD). A good detector system must have two important goals, low Computational Complexity (CC) and good Symbol Error Rate (SER) performance). To achieve that two important goals, our work divided into two parts. The first part, by using an unequal power transmission (UEPT) scheme in instead of equal power transmission (EPT) scheme to get a good SER. The second part, how to reduced CC, this achieved by changing the Euclidean Distance (ED) by using Manhattan Distance (MD). The simulation results show us a slight improvement in the SER performance of about 1.1 dB as average gain and a good reduction in CC about 24% as average reduction in visited nodes when using the UEPT with MD against using EPT with ED.