The Arkua 6158 uses a small 10mm thick 60mm fan rotating at a low RPM so it is one of the quieter heatsinks we've seen in a while. If you really want to hear the difference this fan makes, go to our review of the Arkua 6258 and compare the Acoustic sample with this one of the 6158.

Synthetic Temperature Test Results: *Ranked according to 100W small interface die test results.

FrostyTech Synthetic Temperature Test Platform Results
	Mfg.	Model	Ambient Temp.	27mm large copper block	15mm small copper block		27mm large copper block	15mm small copper block	Thermal pad	No. Fans	Fan Noise	Clip force
				50W	50W		100W	100W
1	Arkua	7228	23.1	37.3	39.4		52.0	57.2	none	1	loud	easy
2	Arkua	6258	22.6	38.4	41.8		55.0	61.9	blue	1	loud	med
3	Thermal Integration	TI-V77L	26.5	39.1	44.4		57.5	63.6	grey	1	med	med
4	Coolermaster	HCC-002	22.0	41.0	45.8		54.6	66.3	none	1	loud	easy
5	Vantec	CCK-6027D	27.4	45.4	49.6		64.9	73.4	none	1	med	med
6	OCZ	Dominator	26.5	37.7	50.9		52.4	74.2	none	1	loud	med
7	Akasa	Silver Mountain	26.6	46.2	51.5		65.0	76.1	none	1	loud	med
8	Vantec	CCK-6035D-Retail	26.5	44.2	52.8		63.2	77.9	none	1	loud	med
9	Arkua	6158	22.5	43.5	51.0		67.5	78.6	blue	1	low	easy
10	Thermaltake	Volcano 6cu+	26.5	40.3	55.3		58.6	84.4	carbon	1	loud	med
11	Spire	5T060B1H3R	26.7	42.7	57.5		64.6	85.1	none	1	low	med
				50W	50W		100W	100W

Ouch! That little fan looses a lot of ground to the 6258 and its 25mm thick fan. The Arkua 6158 in this particular configuration drops down the level of a good cooler, still above the OEM class, but not in the performance level by any means. This is the trade off for a quiet cooler however. Either sacrifice cooling ability for less noise, or sacrifice quiet for increased cooling ability. There is really no way to win both sides of the game - yet anyway.