In my computer the fan is to noisy - Dell OptiPlex GX280 PC Desktop

Change the fan.

replace it

Terry

The noise could be from dust that gets in cpu fan or power supply fan. Clean them but do not open the power supply. Better replace your power supply.

http://pcsupport.about.com/od/nonworkingcomponent/ht/fannoisetb.htm

If you used compressed air, the fan maybe was rotating too much when you blowed it. If you damaged it, replace it.

fujtsu lifebook's tend to have a noisy fan

Two common factors why CPU fans are noisy:

1. The collected dusts under your fans.
2. Your computer is running over the neutral power that your Power supply can handle, i.e. overclocking, high graphical games and videos.

solutions:
1. clean fans (power supply fans, exhaust and others)
2. replace CPU fans with branded and proven to be quite fans.. it may be an additional cost but proves to be very silent. :)

Most computer stores have one that will fit they are pretty much std items.

It could very well be the noisy fan. Try tapping the computer lightly to see if the noise stops or changes to confirm if it indeed is the fan. Or it could be a noisy HDD.  There is nothing you can do about a noisy HDD but about a noisy fan you can stop worrying as it will cause no probs as long as it is working, noisily or otherwise. You will have to tolerate it. Sometimes it is the detatchable sides of the computer (you wrote 'computer' in your question). See if the noise stops or lessens when you touch the sides a little harder.

If it's the processor fan that's noisy you can purchase a replacement. The fan and heatsink are normally a complete assembly you can find from many vendors online. This computer has a type AM2 socket; you need to make sure to get a cooling fan for that type. Be sure the replacement will fit into the same space as the original.

If it's the power supply fan thats loud, there may be a couple of possible causes. It may just be a noisy fan, in which case you can replace the power supply. Make sure to get one that has at least the same power rating as the original. Or the fan may be running at its maximum speed. I don't know about this computer in particular, but many computers control the fan speed depending on how hot the processor is (determined by sensors built into the main board). If the fan is running at its top speed, it can be quite noisy. This might be due to a defective power supply or problems with the fan control on the system board

Buy a new one here for $10

http://cgi.ebay.com/NEW-DELL-DIMENSION-2350-2300-CASE-FAN-92mm-x-25mm_W0QQitemZ250245854784QQcmdZViewItem