Surface Roughness Comparator:

Surface finish is an important factor that we all look for when holding a new heatsink. Flipping a cooler over to see how well the base has been machined is a quick way to judge the attention to detail that was put into making it. The following FrostyTech Surface Roughness Comparator offers a concise cross section common machine surface finishes. Not every heatsink base will fit into the envelope of this gage, but it does offer a very handy set of representations.

This commercially available gage has 22 machined surfaces from 2 to 500 microinches; Lapped (2, 4, and 8 µ" RA), Ground (8, 16, 32, and 63 µ" RA), Blanchard Ground (16 and 32 µ" RA), Shape Turned (32, 63, 125, 250, and 500 µ" RA), Profiled (63, 125, 250, and 500 µ" RA), and Milled (63, 125, 250, and 500 µ" RA).

FrostyTech Surface Roughness Comparator
The base of a heatsink plays an important role in how well the cooling apparatus interfaces with the processor. Poor surface roughness will affect a good heatsink just as much as a good surface finish will improve thermal conductivity. In an effort to put a more quantitative spin on the comments we provide about base finishes, FrostyTech has begun using a Surface Roughness Comparator. Move your mouse over the image above to see an example at right. Numbers are in Microinches, and finishes from 2 microinches to 32 microinches are excellent-to-good.
Evaluation Notes:
The Thermalright SLK-900A heatsink had a surface roughness of approximately 32M, which is considered good. Move your mouse over the 63M tab above to see a large scan of what this surface roughness looks similar to.

Acoustic Samples: Listen to this Heatsink!

The large 80mm fan that the SLK-900A was tested with doesn't make all that much noise, and in most cases would not be audible outside the PC chassis. To listen to this heatsink for yourself in operation, be sure to click on the little headphones icon below and download the Acoustic Sample MP3 file.

(high) 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. Measurements are made on the dB (A) scale.

FrostyTech Sound Level Results
-	Manufacturer	Model	Noise Level	Scale
	Verax (low RPM)	P14Cu	31.2 dB	Quiet
	Verax	P11T	35.3 dB
	Spire	SPA04B4	35.3 dB
	Spire	5U213C1H3G	35.7 dB
	Titan	D9TBCu35R1	37.6 dB
	ArcticCooling	CuSilent2	37.9 dB
	Aopen	ACK7L	40.4 dB
	Thermalright	SK-7	42.8 dB
	Thermalright	SLK-900A	43.0 dB
	Coolermaster	HSC-V62	43.7 dB
	Akasa	AK821	44.2 dB
	Spire	5F263	44.5 dB
	Zalman	All Flower HSF	47.4/28.9 dB
	Arkua	728M-7N01	48.2 dB
	Taisol	CGK760092	48.4 dB
	Cho-Liang	CB0307U-17	49.5 dB
	Titan	TTC-CU9TB/SC	50.5 dB
	Taisol	CEK787172	50.7 dB
	nPowerTek	TTIC NPH-2	50.7 dB
	Arkua	628	50.7 dB
	Scythe	Kamakaze	51.0 dB
	Tocools	Novasonic	52.2 dB
	Tocools	Novasonic-AlCu	52.4 dB
	Thermal Integration	TI-V77L	53.0 dB
	Sibak	AE01625B	58.2 dB
	AVC	Tundra 2	58.4 dB
	Sibak	AC02625B	59.7 dB
	Coolermaster	HHC-001	59.9 dB
	Sibak	AC06725TH	62.4 dB
	Dynatron	DC1206BMP	65.1 dB
	Thermalright	SLK800	66.2 dB
	Thermalright	AX-7	66.4 dB	louder

With a sound meter you can measure the exact decibel output of a particular fan from a set distance. To keep comparisons consistent, that distance should always remain constant. In this case, the Thermalright SLK-900A measures in with a noise output of 43.0 dBA.