It's the model...we have a Dimension 3000 as well that is extremely noisy (the cpu fan). Our other Dell models do not have this problem. Dell has replaced the fan twice with no effect. Dell, can you please fix this problem with a BIOS update or replace our computer with a different model??
is it loud as soon as you turn on the pc, or does it gradually get louder. If it gradually gets louder, try my solution by adding in another fan in the front of the case to bring in cool air. Remember to point the fan inward so that the airflow goes in to bring cool air in the pc. it says airflow with an arrow on the side of the fan. www.geocities.com/ravipcplanet/ i did it on my 2400. they have the same or similar chassis.