GPU clusters don’t fail from sustained load. They fail on transitions. A pod idling at 20 kW can step toward 300 kW quickly when training begins. The peak matters, but the killer is the step: the dP/dt that forces every layer of the electrical path to react at once. Thermals matter too—but they’re secondary and collateral. Power transients can push protection and control behavior in cycles. Thermal consequences show up later as throttling, efficiency loss, and “mysteriously slower training” that looks like a software problem until you instrument the facility. ...