In this paper we compare the average energy consumption per bit of matrix–vector multiplier crossbar (MVMC) and Benes optical packet switches realized in semiconductor optical amplifier (SOA) technology. Sophisticated analytical models are introduced to evaluate the power consumption versus the offered traffic, the main switch parameters, and the used device characteristics. We also study the impact that the amplifier spontaneous emission (ASE) noise generated by a transmission system has on the power consumption of the MVMC and Benes switches due to the gain saturation of the SOAs used to realize the switching fabric. We show that for large size, a Benes switch is more effective in power consumption than an MVMC switch under conditions of low ASE noise and when the power consumption of turned off SOAs is taken into account. As a matter of example for 64 × 64 switches supporting 64 wavelengths and offered traffic equal to 0.8, the average energy consumption values are $6.24\times 10^{-1}$ nJ/bit and $4.87\times 10^{-1}$ nJ/bit for MVMC and Benes switches, respectively.