Scythe pushes towards Infinity (renamed Mugen)

TESTING

Test Platform

• Intel P4-2.8A The Thermal Design Power of this P4-2.8 (533 MHz bus) is 68.4 or 69.7W depending on the version. As the CPU is a demo model without normal markings, it's not clear which version it is, so we'll round the number off to ~69W. The Maximum Power, as calculated by CPUHeat & CPUMSR, is 79W.
• AOpen AX4GE Max motherboard - Intel 845GE Chipset; built-in VGA. The on-die CPU thermal diode monitoring system reads 2°C too high, so all readings are compensated up by this amount.
• OCZ DDRAM PC-4000, 512 MB
• Seagate Barracuda IV 40G 1-platter drive (in Smart Drive)
• Seasonic Super Tornado 300 (Rev. A1)
• Arctic Silver Ceramique Thermal Compound
• Nexus Real Silent 92mm fan
• Two-level plywood platform with foam damping feet. Motherboard on top; most other components below. Eases heatsink changes and setup.

Measurement & Analysis Tools

• CPUBurn processor stress software
• SpeedFan version 4.22 software to show CPU temperature
• A custom-built variable DC power supply that allows us to dial in exactly what voltage is powering the fan
• Neiko Digital Laser Tachometer to measure fan RPM
• A digital caliper micrometer to measure fin thickness
• B&K model 1613 sound level meter

Noise measurements were made with the fan powered from the lab variable DC power supply while the rest of the system was off to ensure that system noise did not skew the measurements.

Load testing was accomplished using CPUBurn to stress the processor, and the graph function in SpeedFan was used to make sure that the load temperature was stable for at least ten minutes. Every fan was tested at four voltages: 5V, 7V, 9V, and 12V, representing a full cross-section of the fan's airflow and noise performance.

The ambient conditions during testing were 16 dBA and 24°C.

TEST RESULTS

The fan included with the Infinity is one of the quietest stock fans we've ever seen, and is similar in many respects to our reference Nexus 120mm fan. The two fans spin at almost exactly the same speed, with the Infinity's fan just slightly faster at full voltage. They move similar amounts of air, and they performed identically on the test bench.

From a noise perspective, the Nexus was clearly superior. It sounded smoother and softer, and was audibly quieter at a given voltage. The difference was most audible when the fans were spinning at close to full voltage. Both fans were inaudible from one meter at 5V and just barely audible at 7V.

Unfortunately, our sample of the stock fan appeared to be damaged, and developed an audible clicking when held at certain angles. At lower voltages, the clicking turned into a chuffing, but we do not believe that the noise was normal.

Two thermal tests were run with each fan: One with the fan installed on the wide side and one on the narrow. As mentioned, the two fans performed identically in both tests.

Fan @ 12V: The stock fan was quiet at full speed. This is a highly unusual comment for SPCR; the Infinity is one of a very small selection of heatsinks we would consider acceptable at full speed. That's not to say things can't be improved — it wasn't inaudible — but it was quieter than any other heatsink/fan we can think of.

The noise consisted of a smooth midrange hum that was quite easy to tune out. Compared to the Nexus fan, the stock fan sounded more tonal but produced less turbulence noise.

Performance was very good no matter how the fan was mounted (there was very little difference), but not record-breaking. At this level of airflow, the Ninja still outperformed the Infinity by about four degrees. However, keep in mind that, even at full speed, the stock fan still qualifies as a low airflow fan. At higher airflow (and noise) levels, we would expect the Infinity to do better.

Fan @ 9V: At this level, the stock fan was roughly as loud as the Nexus at full speed, although the Nexus still managed to sound a bit softer. As before, the noise was a tonal hum with little turbulence It is a challenge to build a system that is quieter than the fan at this level — for many people, there may be no acoustic benefit to turning down the fan below this point.

Performance remained very good, although there was now a noticeable gap between the two different mountings. With the fan mounted on the wide side, the performance drop from 12V was marginal, but this was not true of the other configuration.

Fan @ 7V: At this level, the Nexus fan was inaudible from one meter, and the stock fan very nearly so. In either case, there would be little point in reducing the fan speed any more. In a system with other sources of noise, the difference would not be heard. Only a very low frequency hum let us know that the stock fan was spinning, and that was audible only when closely listened for.

The Infinity continued to show very good performance with low airflow, losing only three degrees off the performance at full speed. With the fan installed on the narrow end, this gap was five degrees — still an impressive result even if not quite a showcase of what the Infinity is really capable of.

Interestingly, the performance gap between the Ninja and the Infinity was smaller at 7V than it was at full speed. With only 0.03 °C/W separating the two heatsinks, it's too close to call, especially considering that the Ninja had the advantage of being tested at a lower ambient temperature.

Fan @ 5V: Both fans were inaudible from one meter at this level. If you want to guarantee that you won't hear the Infinity, running the fan at five volts is a good way to do it.

And, unlike most heatsinks, the Infinity should be able to handle this little airflow unless your processor is especially hot. Our test processor was well beneath its throttle point, and would likely remain so even in the thermal constraints of an actual system.

One drawback: Performance with the fan mounted on the narrow end suffered significantly at this level. Even so, with a reasonably cool processor it might still be good enough, especially with the help of a little system airflow. We would not recommend trying to cool a hot processor in this way though.

INFINITY VS. NINJA

The obvious competitor for the Infinity is Scythe's own Ninja. Our test of the Ninja used a Nexus 120mm fan, which, as we showed above performs almost identically to the stock fan. Both the Infinity and the Ninja Plus come with the same stock fan, so this comparison can be used to judge between the two heatsinks in their stock form.

While both heatsinks are clearly excellent performers, a side by side comparison leaves no doubt that our Ninja sample is the better of the two — at least with low airflow. The difference is not great, but it is there.

Nevertheless, we should stress that these results apply specifically to low airflow situations that are of interest to silencers. It seems quite likely that the Infinity could reverse the standings if the two were tested with a noisy, high speed fan, as it would be helped by its larger size and the closely spaced fins around the heatpipes. [Editor's Note: It's also possible that our sample of the Ninja is unusually good. Recently, we've learned that sample variiance in heatpipe production is high enough to affect the actual cooling performance of many heatsinks.]

Keep in mind that on our hotter 775 test platform, the Ninja was recently edged by Thermalright's Ultra 120. This suggests that the Infinity would be surpassed in performance by the Ultra 120 as well.

NOISE RECORDINGS IN MP3 FORMAT

Scythe Infinity: 5V-7V-9V-12V, 5s Ambient between levels: One Meter, One Foot

Note: Our sample of the Infinity appeared to be damaged, and developed a clicking under certain conditions. This clicking can be heard at the end of the one foot recording.

Comparatives:

Arctic Cooling Alpine 64: 5V-7V-9V-12V, 5s Ambient between levels: One Meter, One Foot

Scythe Mine w/ stock fan: 5V-7V-9V-12V, 5s Ambient between levels: One Meter, One Foot

Nexus 120mm fan: 5V-7V-9V-12V, 5s Ambient between levels: One Meter, One Foot

FINAL CONCLUSIONS

The Infinity is big enough to cool just about anything, even with low airflow. Even if it cannot beat our Ninja or Thermalright Ultra-120 samples, it's still a very good heatsink.

The Infinity's biggest advantage over the Ninja is its mounting system, which is easy to use, doesn't require any tools, and doesn't require removing the motherboard. It also supports AM2 — which the Ninja does not... yet. On the other hand, the Ninja has several advantages of its own: It's smaller, lighter, and is therefore likely to be more widely compatible. And, despite being difficult to use, its mounting system seems more secure.

In the end, it's best just to evaluate the Infinity on its own merits. The Infinity is a very quiet, well-performing heatsink that is easy to use. It should be able to cool just about any processor with a minimum of noise. So long as compatibility issues can be avoided, it is a solid choice for a quiet system.

Much thanks to Scythe USA for the Infinity sample.

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