it pulls around 400W
Try dropping the power cap on your GPU if it supports it; you can often get much lower energy usage with minimal loss of tok/s (particularly during generation) than whatever the GPU defaults to. There's a sweet spot around 200W on the GPU I'm currently testing that gives me about ~75% of the max pp and 97% of tg while using 100W less than the default/max 300W power cap -- and the card runs much quieter as a result.