Really can't say for certain, as I am not familiar with the specific hardware. However, that is the method I would begin to troubleshoot. Make certain it is the monitors that are causing the surge, and work from there. If the old monitors put back in cause the same surge, it's possible some settings may have been changed by the new drivers?
As I said, if it is indeed the monitor, go into control display settings and cut the resolution way down. That will decrease some of the internal clocks that my be causing large power draw. Enough so, that you can see if the new monitors are directly 'causing' the spike in draw.