NB Fan broken? Creepy things happened

[angie]

My computer turned itself off. After several attempts at turning it back on (it just turned back off), I got it on and went in the BIOS. CPU temperature was 98 CELSIUS and system temp was 58 C. CPU fan was fine, and CPU temp went down to 68 in less than a minute, but NB fan was not on. I opened it up and discovered CPU fan was partially unplugged from power, so I plugged it back in. NB fan had a lot of friction, must have been what made it stop.

But why did my CPU get the heat? Did both fans coincidentally stop working at once?

Anyway, I have other problems now. I took off the NB fan and found it was cracked and looked burned. But I can't get the heatsink off. It's on some kind of plastic cylinders which I think contain springs. I can pull it off the mobo, but nothing else. Paste this image URL in your browser to see:

img465.imageshack.us/img465/1353/nbzm1.png

How do I detach this thing, and how do I know which NB fans/heatsinks are compatible with my mobo?

System:
MSI P4N Diamond (MS-7160) <--this is an nforce SLI Intel edition
Pentium 4 3.2 GHz
2GB Corsair RAM
2xGeForce 7800 GTX OC
On-board SBlaster Live!
Nothing is overclocked. Was, but I turned it back to normal recently.

[Blitzen]

Which mobo do you have?

[angie]

An MSI P4N Diamond (listed above since edit).

[frazered]

there are some clips on the back of the mobo which need to be prised to release the nb fan

the zalman nb heatsinks are compatible as are the vantec revo's

[BUFF]

It's on some kind of plastic cylinders which I think contain springs. I can pull it off the mobo, but nothing else.

probably sprung pins.
These have little barbs that splay out behind the PCB & the springs keep them up against the PCB.

2 ways:
snip through them if you have replacements.
remove mobo from case & squeeze the barbs shut allowing them to be withdrawn through the PCB

[angie]

Thank you! Perfect answers, to be implemented immediately. BTW, my computer runs fine without the NB fan (I got impatient). I think recent unexplained system instability is probably due to the broken fan.