The +12V should be around, well, 12V, and the vCore should also be pretty stable as well. I don't think you can look at them both at the same time...they'll both just look like little squiggles.
The 3.3V rail looks fine as well. Yes, speedfan has a logging facility and it wouldn't be a bad idea to check the rails under load. The help file has more information, but basically you need to go to Configure -> Log -> Enabled, and then select the Temperatures and Voltages to be logged.