Help needed to identify CPU fan

Hi

Please forgive me on the length of my post.

Hope I am not asking a stupid question. I am having a bit of a problem identifying fans in SpeedFan.

I just replaced my northbridge fan with a passive cooler.

In speed fan, I have;
Temp1
Temp2
Temp3
HD0

Under Zero Load;

Temp1 = 25C
Temp2 = 23C
Temp3 = 27C
HD0 = 20C

Under 4M superPi (just beofore the run finishes)

Temp1 = 31C (delta 6C)
Temp2 = 24C (delta 1C)
Temp3 = 36C (delta 9C)
HD0 = 21C (delta 1C)

Do you think that it would be correct to assume the following, given, the temperatures above.

Temp1 = Northbridge
Temp2 = Unknown
Temp3 = CPU

Im not sure what the Temp2 would be coming from. If its any info, I have the following kit.

CPU: 3800+ X2 @2.00GHz
CPU FAN:arctic cooling, 64 Pro
MOBO: Asus A8N SLI-SE
GPU:7900gt, With Zalman VF900-Cu (at lower rpm setting)
2 120mm fans, one at the front, one at the back.

While I am here,

As far as my GPU goes, under high load, the temp is 40C.

I guess the second part of the post would be, do these temps look ok?

The ambient room temp is about 18C.

And lastly, when I booted after replacing the northbridge with a passive cooler, I was greeted with a warning about 'a' fan. And asked me to fress F1 to continue. I know that I can stop this notice in the setup.

This is the Northbridge fan is it not?

Thank you for getting to this part, i always write too much

Rob