Heat: Passive Cooling, if You'd Like!

In theory, it's great that our Core 2 Duo E6300 draws 17.8% less power under full load - but what does that mean in practice? We decided to track the processor's heat buildup over time with the cooler's fan turned off to see what the real-world payoff was.

In our first round of tests, we used the stock cooler that ships with the boxed version and put the CPU under full load.

The Zalman CNPS9700

After 3 minutes 15 seconds, the B2 stepping began to reduce its speed due to overheating (87°C), protecting itself by throttling the clock speed.

By comparison, the L2 stepping held out a full 5 minutes before its internal heat sensor triggered the throttling feature.

In our second test, we replaced Intel's stock cooler with a Zalman CNPS9700, once again disconnecting the fan.

This time, the B2 stepping takes much longer to heat up. However, at 8 minutes 30 seconds, it once again begins to reduce its clock speed.

The L2 stepping, on the other hand, would get by just fine with passive cooling. Even after 15 minutes at full load, the temperature stayed just under 82°C with the Zalman CNPS9700 - apparently low enough to avoid clock speed throttling, as the CPU continued at full speed. Intel's documentation states a TDP of 61.4°C. Since the CPU's core temperature is typically allowed to be about 10°C higher, meaning the processor is running out of spec. In combination with a cooler designed specifically with passive cooling in mind, this processor could operate silently and well within its specifications without a problem.

Thermaltake is one of the companies that offer passive CPU coolers, such as the Sonic Tower.