Sorry for double posting, my browser doesn't like to let me edit posts. (?)
Anyways, as far as temperature monitoring, I've been using SpeedFan. The +12V value it gave me with my X-Finity 500w was way too high (13+ volts, way over ATX spec) and then that PSU failed on me (I doubt it was from "13v" on the "+12v" rail because the BIOS read +12v as like 12.14 -- normal)
Anyways, on my backup PSU (Antec 350w, pre-True/SmartPower era like circa 1999 LOL) SpeedFan is reading 12.4-12.5 which is closer to being believed, but I still doubt it's accurate.
+3.3 and +5.0 are believable, though. It reads the temperature directly from the die so the CPU temp is accurate, I guessed the other realistic temperature sensor on the motherboard is the case temperature (or motherboard?)