Pentium buyers still must pay careful attention to how systems designers dissipate the heat generated by these fast CPUs. The original 5-V 60-MHz Pentium chip runs hot enough to force designers to use both a heat sink and a CPU fan (typically mounted on top of the heat sink) to maximize cooling and ventilation. These small fans, attached to the system's power supply, force air down onto the Pentium processor.
The newer 3.3-V 90- and 100-MHz Pentium chips run cooler but require a large heat sink, which some designers still pair with a fan. The combinations of heat sinks and fans are generally effective but often clumsily placed, in some cases blocking as many as three of the available adapter slots. Another option we saw was a fan mounted at the front of the motherboard to blow air around the interior of the system.
We saw a l
ot of variety in the ways heat sinks and fans are attached. Some fans, including the one used by Tangent in its PCI 566 system, clip onto the CPU with a sturdy wire. Others, such as the one in Austin Direct's P5-66 System, are simply glued to the processor. In at least one case, the fan in the Cornell Pentium EISA Power Pak failed, and the glue melted as the 66-MHz chip began to overheat.
The small plastic fans, which amount to an investment of $10 to $20 each for systems vendors, command a small price for peace of mind for systems that average $5000 and higher. But given the fan failures we saw during our testing, it's wise to open systems regularly to check on fan performance, especially if you leave your system running all the time.
A better idea found on some high-end Pentium servers, such as Compaq's ProLiant, is a thermostat that triggers an alarm process should the system's internal temperature climb above normal. You can also buy a third-party fan unit with a thermostat that performs the
same function.
Illustration: Hewlett-Packard Vectra XU's heat sink
Illustration: Hertz P 6e fan and chip combination
Beating the Heat
