i just switched out my heatsink to the Scythe Kozuti. It made a small difference in the idle temperature (about 1 degree), the big change was in the temps at load which for me means surfing while streaming hd video over HDHomeRun Prime. With the Noctua heatsink, my temps were running 60-63, with the Kozuti they are in the low 50s. I attribute the difference to 1) the Noctua fins run parallel to the side fans on the e-i7 and 2) the Noctua is also very closed form and seems to retain a lot of the heat.
I do see significant random voltage variations still, even at idle. At times package voltage (according to HWMonitor) jumps from 14v to 40-50v for no apparent reason, which also results in temp spike. Do you have the same experience with the 180w powerboard?
Update -- just watched hdtv for 1.5 hours, temps running 60-65, HWmonitor indicated a spike to 72. I don't have any answers at this point, just questions. Have you checked temps after extended use?