Rules of Thumb for cooling AMD processors. Taken from
AMD Athlon System Cooling Guidelines
1. Use an adequate heatsink, sized for the processor speed you are using. Make certain it has the proper sized fan(s). Check the AMD Athlon Prcoessor Recommended Heatsink Page for specifics.
2. Make sure the thermal compoud (grease, phase-change or pads) you use is recommended by AMD. If you use a recommended heatsink, it is normally already included.
3. Use an auxiliary exhaust rear chassis fan, suggested size of 80 millimeters or larger. The fan intake should be near the location of the processor.
4. For best results, use an ATX power supply with air intake venting in the processor region (that means the primary air-intake is on the bottom of the power supply, not at the front of the power supply). Supplies with NLX-style venting (primary air intake is at the front of the power supply) do not pull air from the procesor area!
5. Make sure all the internal wires and cables are routed carefully so as to not block or hinder airflow through the case. Use tie-wraps judiciously to accomplish this.
6. Many cards generate a lot of heat (AGP cards in particular). Try to either leave the slot next to these cards open, or use a shorter card in these slots to allow airflow around cards that are heat producers-typically those cards with many electrical components.
7. High-speed hard-drives (especially 10,000RPM SCSI hard drives) produce a great deal of heat. One way to minimize any problems with these drivers is to mount them in 5.25" frames and install them in the larger drive bays, which allows a greater airflow around them, and can cool them more effectively.
8. A front cooling fan does not seem to be essential. In fact, in some extreme situations, testing showed these fans to be recirculating hot air rather than introducing cool air.