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

FrostyTech Synthetic Temperature Test Platform Results
Mfg.	Model	Ambient Temp.	27mm large copper block		27mm large copper block	Thermal pad	No. Fans	Fan Noise	Clip force
			50W		100W
Thermalright (high)	SLK-900U	20.0	31.6		40.5	none	1	very loud	easy
JMC	401100	19.5	35.1		47.4	grey	1	med	easy
Zalman	CNPS7000-Cu	21.0	35.1		48.7	none	1	low	easy
Taisol	CCP445172	20.2	37.7		50.9	none	1	med	easy
AVC	117140	22.6	37.8		50.4	none	1	med	med
Coolermaster	IHC-H71	23.0	37.0		51.1	none	1	loud	stiff
Arkua	8568	22.4	37.8		51.7	none	1	med	med
Thermal Integration (high)	TI-V7035TN	20.2	38.3		52.9	none	1	very loud	easy
Dynatron	DC1206BMY	19.5	38.1		53.1	none	1	med	easy
Dynatron	DC1207BMX	20.9	38.1		53.3	none	1	med	easy
Alpha	PAL8942	27.9	42.6		54.0	none	1	med	med
CoolJag	JVC661A	23.2	40.5		56.7	none	1	med	easy
Spire	SP411C5	25.2	42.5		56.9	white	1	loud	easy
Zalman	CNPS6500-AlCu	23.1	40.3		57.4	none	1	low	easy
Taisol	CEP426151A	24.3	43.7		59.7	none	1	med	easy
Intel	Socket 478	22.4	41.8		59.8	carbon	1	low	med
Arkua	838T-7G	23.3	42.0		60.0	none	1	med	easy
Dynatron	DC1207BMW	23.2	42.7		61.1	none	1	med	easy
Spire	SP420B8	25.3	42.7		61.5	none	1	low	easy
Dynatron	DC1206BM-S	22.4	43.2		62.0	none	1	med	med
AVC	117160	22.4	42.7		62.2	white pad	1	med	med
Evercool	NW9F715CA	23.8	42.9		62.3	none	1	med	easy
Zalman	CNPS5700D-Cu	25.7	44.6		64.0	none	1	med	easy
Globalwin	VA476	28.7	49.5		68.0	grey	1	med	easy
Dynatron	DC1206BMV	23.1	45.1		68.2	none	1	low	easy
Vantec	GSN-7015	22.4	47.5		69.0	none	1	loud	stiff
Verax	P16	21.8	49.2		75.8	none	1	none	med
Arkua	848X-6B	27.2	54.5		80.4	none	1	low	med
Dynatron	DC1U-B02	20.9	53.8		88.3	none	1	loud	stiff
			50W		100W

Low noise heatsinks are rarely if ever in the top 10 positions for the very simple fact that they move less air. The more air that flows across the fins, the better the heatsink can perform, typically. There are plenty of exceptions to this rule, and for a long time adding a faster (and louder fan) was seen as a viable upgrade. I don't quite agree with that notion, but you can't argue with the fact that the Spire SP420B8 provides good cooling with virtually no noise.

Rise Above Ambient Temp. (c)
Mfg.	Model	27mm large copper block		27mm large copper block
		50W		100W
Thermalright (high)	SLK-900U	11.6		20.5
Alpha	PAL8942	14.7		26.1
Zalman	CNPS7000-Cu	14.1		27.7
AVC	117140	15.2		27.8
JMC	401100	15.6		27.9
Coolermaster	IHC-H71	14.0		28.1
Arkua	8568	15.4		29.3
Spire	SP411C5	17.3		31.7
Taisol	CCP445172	17.5		30.7
Dynatron	DC1207BMX	17.2		32.4
Thermal Integration (high)	TI-V7035TN	18.1		32.7
Cooljag	JVC661A	17.3		33.5
Dynatron	DC1206BMY	18.6		33.6
Zalman	CNPS6500-AlCu	17.2		34.3
Taisol	CEP426151A	19.4		35.4
Spire	SP420B8	17.4		36.2
Arkua	838T-7G	18.7		36.7
Intel	Socket 478	19.4		37.4
Dynatron	DC1207BMW	19.5		37.9
Zalman	CNPS5700D-Cu	18.9		38.3
Evercool	NW9F715CA	19.1		38.5
Globalwin	VA476	20.8		39.3
Dynatron	DC1206BM-S	20.8		39.6
AVC	117160	20.3		39.8
Dynatron	DC1206BMV	22.0		45.1
Vantec	GSN-7105	25.1		46.6
Arkua	848X-6B	27.3		53.2
Verax	P16	27.4		54.0
Dynatron	DC1U-B02	32.9		67.4
		50W		100W

The all-copper Spire SP420B8 performs at about mid-level for this list of reference heatsinks. Sure it doesn't come in at the top position, but then again have you heard how loud that thermalright SLK900U is with the fan that produced those numbers?!

Given the compact size, and simplicity of not requiring any extra mounting hardware (or oversized dimensions), the Spire SP420B8 fills in the necessary gap. It's made of copper to make up for the 2500 RPM fan, and because of that it is able to keep up. An overclockers heatsink it is not, but for any mainstream user this little cooler should be just fine. Though, if you're moving from a vacuum cleaner to something of this level, you might just wonder why you don't hear a thing anymore!

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2. Dynatron DC1206BM-V 1U Heatsink
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4. Arkua 848X-6B 1U Heatsink Review
5. Thermalright AX-7 Socket A heatsink