Overclocking often raises the power consumption, between more clocks per second, and often needing to raise the voltage to be able to "charge" the internals faster to be able to get them to switch at the higher clock rate.
20 dBm is 0.1 W of RF out, 30 dBm is 1 W. If you're using the wireless heavily, seeing an increase in power consumption over the bootloader isn't out of the ordinary.
Having to run on backup power here more often than I care, lower power consumption is something I do pay attention to. My Archer C7s run around 1-2W during boot, 3-4 W at idle, and a tad higher with heavy wireless activity. Assuming you trust a "Kill-A-Watt" to be able to measure with any accuracy at those levels.
Does your switch allow you to enable "energy efficient" Ethernet?
Is your power supply ("wall wart") efficiency Class VI or better? That might gain you 20% or so, depending on the efficiency of your supply and if it is oversized or not.
I'm assuming you don't have any USB devices. They can consume significant power compared to a Watt.
Turning off the LEDs might gain you a fraction of a Watt as well.