With Zilliqa, PoW will be applied to multiple blocks at the same time instead of just one, which both saves energy and benefits miners.
Each month, Zilliqa will need about 12 hours for total PoW operations (at the beginning of each epoch cycle), at this time the graphics card will run at full capacity. However, for the rest of the time, the graphic card will run in low power mode and the power consumption will be minimal.