Fan speed for Intel Pentium IV 3.2G 800mHz FSB

I have purchased my PC 3 years ago. Recently it is giving me problems - frequently shut down after 3 to 4 hrs. I checked CPU temperature, it goes up to 90°C when it shuts down, with the fan speed of 2500-2600rpm. I cleaned the fans, but there is no improvement. I think the fan speed should be around 5000rpm when it's new, and the speed has dropped. In this case, I think I will just have to replace the CPU fan.

My CPU is Intel Pentium IV 3.2G 800mHz FSB.

I am not sure if my theory is correct.

And I have just checked online for stores that sells fans for 478 pin & Intel 3.2GmHz CPU. I could only find cooling fans of 0.25A, but on the User Guide of the motherboard, its stated the motherboard support fans of 0.35A-0.74A. I am not sure if I can use these fans??? If not where can I buy the correct one????

I am currently in Australia and wish to find online shops that can have no problems with payment issues and shipping issues.

Can anyone help??