I am not sure why it is, but OEM fans shipped with retail verions of CPUs operate very quietly and also have an extra pin for control (4 pins in total) so the motherboard can dynamically adjust their speed as needed. 3rd party fans have only 3 pins and usually come with a potentiometer so you may adjust them manually, and at their full speed make a lot of noise.
I have also found that some CPUs heat up considerably, overclocked or not, and the CPU fan would be making a lot of noise trying to keep the temperature down
The solution to this problem came with the purchase of a case that has a 25 cm fan on its side blowing air on the whole motherboard, CPU, chipset and VGA card included. These huge fans spin quite slowly and make no noise at all, and achieve more than 3 noisy 8-12 cm fans put together. All my cases now have these huge fans on the side and even though overclocked, I do not need anything more than the OEM fan on the CPU and no other fans in the case and the whole thing is cool and whisper quiet.
The only thing to watch out for is internal space, my 9500 Zalman CPU fan (bought in error thinking I'd need it and now runs in the lowest setting) rises above the level of expansion cards and leaves no room inside for the 25 cm fan.
I have also found that some CPUs heat up considerably, overclocked or not, and the CPU fan would be making a lot of noise trying to keep the temperature down
The solution to this problem came with the purchase of a case that has a 25 cm fan on its side blowing air on the whole motherboard, CPU, chipset and VGA card included. These huge fans spin quite slowly and make no noise at all, and achieve more than 3 noisy 8-12 cm fans put together. All my cases now have these huge fans on the side and even though overclocked, I do not need anything more than the OEM fan on the CPU and no other fans in the case and the whole thing is cool and whisper quiet.
The only thing to watch out for is internal space, my 9500 Zalman CPU fan (bought in error thinking I'd need it and now runs in the lowest setting) rises above the level of expansion cards and leaves no room inside for the 25 cm fan.