Let's see...8C = 46F. That is nearly as cold as my refrigerator. I don't think air cooled intel chips can be BELOW ambient. This time of year in my part of the world, 25C is more normal ambient, and my E6400 undervolted runs about 32C surfing the net.
And 20C is around 68F...still pretty cool...even running stock!
Do a search for motherboard temperatures. You'll find all sorts of incisive posts about how intel uses diodes and offsetting values.
I suggest trying intel's TAT or Orthos to stess your mobo and use PC Wizard or Everest to monitor your temps. Probably alot more accurate than you're getting now.