Running under normal power levels the CNPS5700D is a bit louder than other Zalman heatsinks, and this is mainly due to the fan duct which creates a bit of air turbulence. The heatsink under quiet mode with the fan mate 1 is pretty quiet indeed. To listen to this heatsink under full power for yourself, click on the little headphones below and download the MP3 file.

FrostyTech Acoustic Sampling Chamber
Standard Waveform view of a 10 second recording. Click on the headphones to listen to an MP3 recording of this heatsink in operation.

Sound Level Measurements:

Listening to the actual noise a heatsink makes allows you to hear what pure numbers alone cannot get across. To further emphasize FrostyTech's reliance on cold hard facts when evaluating a heatsink, we also take Decibel readings with a sound level meter. These results may be higher than the manufacturer's listed specs, but then again these are real world measurements.

FrostyTech Sound Level Results
-	Manufacturer	Model	Noise Level	Scale
	Zalman	CNPS6500-AlCu	47.4/28.9 dB	quiet
	Intel	Socket 478	42.5 dB
	Cho-Liang	CL-CB0094-1A	49.8 dB
	Cho-Liang	CL-CB00881	50.2 dB
	Taisol	CEP426151A	50.7 dB
	Vantec	CCK-7025	51.4 dB
	ChoLiang	CB0307Z17	52.9 dB
	Dynatron	DC1207BMW	53.0 dB
	Zalman	CNPS5700D-Cu	53.8 dB
	Globalwin	VA476	54.2 dB
	Dynatron	DC1206BMV	55.1 dB
	Glacialtech	Igloo 3300	55.4 dB
	ChoLiang	CB0309Z17	55.7 dB
	AVC	117140	56.1 dB
	NengTyi	NW6700	58.0 dB
	Coolermaster	IHC-H71	64.4 dB	louder

At 53.8 dB the CNPS5700D is running at full power. The sound is mostly coming from the air moving about in the air duct. We tried a few trick to quiet this sound down by splitting the duct into two parts but this really only succeeded in limiting the amount air being exhausted.