In order to test how the side duct and the rear fan interfere on the inner temperature of systems based on the Pentium 4 Prescott, we conducted three tests: system assembled with a tower case with side duct, side window (grating allowing air to flow above the motherboard slots) and rear fan; same system with the rear fan turned off; same system with the side duct removed and its hole closed, the side window closed and the rear fan turned off.

The test consisted in measuring two temperatures, processor and "system zone" (area were the MOSFET transistors of the voltage regulator are located), with the case closed, first with the computer turned on but doing nothing and then with the CPU working at 100% of its processing power.

We used an Intel D865GVHZ (P22 BIOS) motherboard together with a Pentium 4 Prescott 2.8 GHz with external frequency of 533 MHz, without Hyper-Threading technology, using the cooler and thermal paste that came with the CPU ("in-a-box" model) and a Seventeam ST-350BKV power supply, all assembled on a Casetek BP-1005 case, which satisfies Intel's requirements for Prescott CPUs.

Figure 7: Equipment used on our tests.

Figure 8: Casetek BP-1005 case.

We measured the temperatures using Intel Active Monitor v1.2.1 program. The testing procedure was to put our CPU running at 100% of its processing capacity using the program CPUBurn v1.4 for 10 minutes. Then we monitored the CPU and "system zone" temperatures for 5 minutes and recorded the average temperatures, measured throught the motherboard thermal diodes. After this process we reduced the CPU usage near 0 %. After 30 minutes we checked if the CPU temperature has stabilized and we started monitoring the CPU and "system zone" temperatures again for five minutes. We also used Throttle Watch program (read our tutorial on this subject) to check if the Thermal Throttling feature was being turned on or not during our tests. The room temperature during our tests was 82º F (28º C).