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Noise levels
Noise levels were measured with an Extech 407727 digital sound level meter placed one inch from the top of the motherboard and out of the path of direct air flow. We tested the Zalman coolers with their highest and lowest fan speed settings to illustrate the range of noise levels one can expect. To ensure consistent results, the motherboard's temperature-based fan speed control was disabled.

The CNPS9500 is about a decibel quieter than Zalman's CNPS7700 with both the high and low fan speed settings. Interestingly, though, both Zalman coolers are louder than a stock AMD cooler at their highest fan speeds.

CPU temperatures
To test the CNPS9500's cooling performance, we subjected our test system to a 30-minute test that consisted of ten minutes of idling, followed by ten minutes of Prime95's maximum heat torture test, followed by ten minutes of idle cooldown. CPU temperatures were logged every second through the entire test.

To make things more difficult for the coolers, we tested with Cool'n'Quiet disabled. We also conducted extended load tests to ensure that our ten-minute Prime95 torture test was long enough for the processor to hit its peak temperature. Tests were conducted on an open test bed with an ambient room temperature of 24C.

We're graphing geeks, so we couldn't resist posting a graph of CPU temperatures over the length of our test. The graph isn't all that easy to read, though, so we've busted it in two to isolate cooling performance with Zalman's high and low fan speed settings. Note that the following graphs don't have a baseline of zero degrees on the Y axis; we've just tried to make them a little easier to read.

Interestingly, while the CNPS9500 is quicker to cool down with both fan speed settings, it heats up faster than the CNPS7700 on the low fan speed setting. The graphs are still a little muddled, though, so we've whipped up some average results for the last minute of the idle, load, and cooldown periods.

Although the CNPS9500 can't quite match the CNPS7700's temperatures at the highest fan speed setting, the 9500 yields lower temps during the idle, load, and cooldown periods at the lower fan speed setting. The CNPS9500 also beats the stock AMD cooler across the board.