The dock has an external monitor, right? Don’t know your laptop, but rather than the power supply I would assume it’s the load that monitor is placing on the GPU Wild speculation of the worst sort, of course

I don't think that's it, for one thing, my laptop screen is off when docked and it's higher resolution than the monitor the dock is driving. And looking at the task manager the GPU usage is higher now than I've ever seen it, plus the fans are going apeshit