Everytime I start my computer my MB temp sensor says 41c (my comuter was just running prime for 2 hours) cpu-z will tell me my cores are at idle temps around 27-30c. I am using the stock 3000+ HSF on athlon II 630 (which came with an awful HSF). So should I just ignore the MB sensor and as it usualy reads 10-20 degrees higher then my processor thermal sensors?
Sounds like your MB might be getting hot with some random stuff not getting activated until you're in windows; maybe your graphics card fan, etc. I have the same processor and I got an aftermarket cooler and I've never seen temps over 35C ever since and I have mine overclocked to about 3.5
Oh, your MB sensor and your processor sensors are different dude. You might wanna move some of your PSU cables around or run 'em around the back of your case so that the air's flowing all the way through. Try to move stuff around like get your HDD away from your graphics card or try getting a better fan. There are apps that show you both temps though I use ASUS probe II when i really wanna know my voltages and temps and I think AMD overdrive does both sensors as well. What kinda MB do you have ?