ive got mine at 1100rpm, but it hovers at about 1200rpm when under little load. With the external monitor connected it sits at about 1600rpm. The standard base speed i think is too high, my temperatures are about 50°C with external monitor in and 45°C without it.
the cpu must warm up a little with the monitor in because the gpu is cooled off the same fan/heatsink meaning if the gpu heatsink heats up then so does the cpu one and then the cpu gets a little warmer as well.