Most of the time, people just blame C1E and Speedstep, because they can. The majority of lockups and instabilities are either not enough voltage or too much voltage.
Yeah, I know, but it only locks up consistently when I'm playing a video file. And no, it's not a conflicting codec, because I only have the base Win7 codecs (which cover just about everything).
I've had plenty BSODs in plenty computers because of energy saving features, not many lockups tho and usually speedstep and C1E are ok is usually the mobo maker's attempt to power saving that doesnt work great. However the C1E voltage changes could cause instability very easy.