Approximately nine months ago, THG stirred up quite a commotion with its article Hot Spot: How Modern Processors Cope With Heat Emergencies . Accompanying the article was our very first downloadable video, which shows the dramatic behavior of an AMD Athlon with a Palomino core, equipped with a thermal diode, when the CPU cooler fails during operation.

The alarms sounded at AMD, and the THG crew met several times with engineers from the manufacturers in question (AMD and Siemens). A few weeks later, AMD introduced a new circuitry logic to a small group of people. This was supposed to turn off the power supply as soon as the die temperature surpassed 85 degrees Celsius.

In order to guarantee faultless protection, the CPU temperature is measured by the thermal diode in very short time intervals, which ensures that the power can be switched off in time. Currently, all motherboard makers have a copy of the new "Thermal Guide" from AMD. Still, only a few manufacturers integrate thermal protection into the older motherboard designs, because this involves huge additional costs.

There are some examples of this to be found in the THG lab. The QDI Kudoz 7X with the VIA KT400 chipset (reviewed here), which arrived recently, implements overheating protection. In this technique, the data for temperature control (thermal diode) is read by the BIOS. The problem with this is that booting a PC without a CPU cooler takes too much time to ensure effective protection, with the result that the Athlon XP/MP CPU dies a thermal death.

Asus currently offers an interesting solution: here, the CPU temperature is monitored entirely with external circuitry on the motherboard. This results in more immediate reaction to temperature changes, nearly free of delay. Booting up without a CPU cooler and without having the CPU burn up is not a problem.

Comparison: T-Bred "B" Vs. T-Bred "A" Vs. Palomino