I bought a new cooling fan for my cpu (AMD Athlon XP 3000+) because I was worried about being above the "safe zone" with stock HSF. I was at 59C usually with it and I decided to purchase a new fan. So yesterday my new fan (Whisper IV) came in and I notice when I go to the BIOS PC Health for a cpu temprature reading it says 61C (2C higher than my stock heatsink ). But when I run Motherboard Monitor I get 38C for cpu and 37 for system. I also tried Sisoft and it says 37C. I tried SpeedFan and it says 38C. So which is right, my bios or these programs? Right now I'm confused, please help.

People usually say to trust the bios more than programs, but I know that's not what you wanted to hear.

How much thermal compound did you use(you did use some right?)? It doesn't take very much at all, too much makes it worse.

I called up cablesunlimited and the guy I spoke to said the reason I'm getting a much lower temperature in the programs is because my bios is set to a certain voltage or something. He said the programs will check for the real temp inspite of voltage. Then he was gonna connect me to another tech but I got some stupid msg and I hung up. But if what he said is true how do I change the default voltage or whatever he said so that my bios can read my real temp?

the thing to consider is the possibility of your sensors being bad all along, thus causing you to mess with your cooling in the first place. how is your case's airflow/ambient temp? if the heat is being conducted from the cpu to the heatsink at an appropriate rate and the fan is moving enough air through the fins, you can assume that your sensors are off and that your processor is running fine.

This is a brand new computer. So I assume nothing is bad. The temperature reading for my system is 37-39C.

just because it's new doesn't mean that the sensors are fine. they could simply be too inaccurate from the start.