In this work, TaOx based ReRAM devices were fabricated by reactive sputtering. The impact of RF power on the device characteristics was investigated using five different RF powers ranging from 116 W (RF 20%) to 356 W (RF 60%), resulting in different film deposition rates. Depending on RF power, both the initial device resistance (Rinitial) and forming voltage (VFORM) were found to be changed. The switching layer sputtered at 116 W shows the highest Rinitial (80 GΩ), whereas the lowest resistance (50 kΩ) is obtained at 236 W. The device RESET level (ROFF) is a function of Rinitial and VFORM. The largest memory window (ROFF / RON ~ 105) and 2-bit MLC operation are achieved at 236 W deposition power. These devices show excellent retention at 125 °C for 104 seconds and good endurance up to 106 cycles. These results reflect the impact of the sputtering deposition power on the electrical performance of the ReRAM devices. It is due to the fact that the structural defects and oxygen content in the deposited film are modulated by the sputtering power.