Review: Kamakaze HSF by Scythe

Cooling
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TEST RESULTS

  • All temperatures in degrees Celsius.
  • CPU: Temp reading from CPU thermal diode, recorded by Intel Active Monitor.
  • Ambient temperature was 23° C throughout the testing. This is the average of temps measured at several points ~2 feet distance around the test platform.

KAMAKAZE, w/stock fan: CPUBurn >20m - Ambient: 23° C

Fan Speed
blowing up
blowing down
CPU
temp rise
° C/W
CPU
temp rise
° C/W
1450 rpm (min)
49
26
0.42
54
31
0.50
2200 rpm (~mid)
45
22
0.36
48
25
0.41
3400 rpm (max)
39
16
0.26
40
17
0.28

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KAMAKAZE, w/Panaflo 80L fan (SPCR reference): CPUBurn >20m

Fan Speed*
blowing up - Ambient: 23° C
CPU
temp rise
° C/W
5V: ~600 rpm
68
45
0.73
7V: ~1050 rpm
54
31
0.50
10V: ~1400 rpm
48
25
0.41
12V: ~1750 rpm
45
22
0.36

* Our Panaflo 80L reference fans do not have RPM signal output. The fan speed of the Panaflo 80L was measured using an RPM sensing device obtained from SPCR Forum member fancontrol. (See this post thread.) As with the stock fan, the Intel Active Monitor software was used to read the RPM output to the motherboared fan header. The accuracy of RPM sensing is such that all of these figures (including the ones for the stock fan) could easily be off +/- 10% and also vary that much for different fan samples

Stock Fan Noise

At minimum speed, the stock fan is very quiet. Its speed is about the same as the recently reviewed Zalman 7000 fan at min, and its noise level is a bit lower. Subjectively it is very similar to the Panaflo at 8~9V. There is a trace of buzzing, but the noise is mostly airflow. The fan noise is said to be 16 dBA at this speed; while this could not be verified, it is certainly plausible.

At the middle setting of the speed control dial, measured as 2200 RPM by the Intel monitoring software, it is still fairly modest in noise level.

At maximum speed, the fan is predictably noisy. It is spec'd to be 37 dBA (presumably at 1 meter). This is probably what the fan is rated for in free air without airflow impedance. It may be higher on the heatsink. There is a lot of turbulence wind noise, and some whining. It is too noisy to be called at all quiet.

Cooling: Stock Fan

The difference in cooling performance with the fan blowing down vs. blowing up is dramatic at lower fan speeds; 4° C is a big difference for such a small change! The HSF seems well-optimized for the recommended blowing up position -- except at the max speed with the stock fan where the temp result is the same either way. So it appears that the blowing up advantage has an inverse relationship to fan speed: The advantage is greater at lower fan speeds.

With the stock fan, the performance at middle and lower speed is of greatest interest. Cooling performance with lower airflow is very good. Not up to the highest standard set by the Zalman 7000s or the Thermalright SLK900, but still quite good.

Cooling performance with the stock fan at full speed is excellent. It is just about as good as the best heatsinks tested by SPCR using a similar airflow fan. Any heatsink approaching a C/W ratio of 0.25 is really superb. It is noisy, but still much quieter than typical >50 cfm fan employed by "top overclocking" heatsinks.

Cooling: Panaflo 80L Fan

Results with the reference Panaflo fan were not as good as with the stock fan, as expected. If the Panaflo is used with this HS in a similar system installed in a real case, 7V is the minimum recommended fan voltage. The Kamakaze's C/W stats with the Panaflo puts it close to the Zalman 6500-AlCu and the Thermalright AX-478.

CONCLUSIONS

Real world conditions are tougher than those in the SPCR lab. When a system is installed in an enclosed case, the ambient temperature is sure to rise at least 5° C, more often 10° C or even more, depending on particulars. Many quiet PC enthusiasts run systems with no case fan or just one low airflow fan. In consideration of these factors, low noise enthusiasts are urged to add 10° C to the test results when trying to guesstimate what their temperatures would be. Even better would be to measure the in-case temperature near the HS fan and use the C/W figures to calculate likely CPU temperatures with the Kamakaze.

It is best to regard the test results not in an absolute way, but rather, as comparative guidelines. The result obtained with this heatsinks will vary greatly on the particulars for each system.

The Scythe Kamakaze HSF provides good quiet cooling with its stock fan at the minimum speed. Being optimized for blowing up fan configuration may be particularly useful for those who wish to experiment with exhaust-to-back panel ducts.

Even without a duct, the blow-up fan configuration can often result in better real-world pefromance because of typical case layout details. Most back panel exhaust holes line up close to the top of the HSF. If the hot air from the CPU is being blown to this area, then a rear case fan can more efficiently exhaust it out of the case, thereby keeping all system temps down.

Given the anticipated pricing of the Kamakaze HSF and the quiet performance at the min speed setting, most buyers will probably use the fan and fan speed controller supplied. As noted earlier, the speed control pot can easily mounted on the front panel of your PC for greater convenience.

The installation procedure for P4 use is a lot more fiddly than with most heatsinks, the biggest bother being the need to swap out the retention bracket. Whether tightening the set screws so that the clamping bar is at full height as per the instruction sheet is questionable.

All in all, the Scythe Kamakaze HSF is a good heatsink full of novel ideas. While it fails to reach the highest levels of P4 quiet HSF performance, it is a solid product that may reward experimenters. Recommended.

Our thanks to Scythe for the Kamakaze HSF sample and their kind support.

NOTE: Scythe is seeking distributors and resellers for the Kamakaze; AFAIK, it is not yet available in North America.

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