bios temps vs third party temps

I have been trying to set some benchmarks for a possible overclock on my Q6600. The problem is that I keep getting vastly differnet temps depending on where I am looking. Speedfan says idle at around 32c. while rmclock says 45c. I checked in the bios which I no wont give me a load temp, but it seems like this should be the most accurate for idle and it says 30C. Which should I believe? I was going to try some other third party utilities after I get new ram(had to rma the first pair). I am running a gigabyte ga p35 ds3r. If rm clock is right then I have almost no room for and overclock because under load it gives me temps over 70C at stock. The heatsink is fine it seems to be making good contact and also only slightly warm.

TAT isn't always accurate. I have idle temps showing at 17C when that is less than the ambient air in the room!

Ill try tat. By the way I was running four instance of orthos and the temps on rm clock were showing 75C at stock even though speedfan was showing 59c after 2 hours. no errors were reported. This makes it seem like rmclock is off because i doubt that the cpu wouldn't have problems with these temps.