Spire Fourier IV heatsink/fan

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Testing was done according to our unique heatsink testing methodology, and the reference fan, a Nexus 92mm, was profiled using our standard fan testing methodology. A summary of the components, tools, and procedures follows below.

Key Components in Heatsink Test Platform:

Test Tools

  • Seasonic Power Angel for measuring AC power at the wall to ensure that the heat output remains consistent.
  • Custom-built, four-channel variable DC power supply, used to regulate the fan speed during the test.
  • Bruel & Kjaer (B&K) model 2203 Sound Level Meter. Used to accurately measure noise down to 20 dBA and below.
  • Various other tools for testing fans, as documented in our standard fan testing methodology.

Software Tools

  • SpeedFan 4.31, used to monitor the on-chip thermal sensor. This sensor is not calibrated, so results are not universally applicable, however.
  • CPUBurn P6, used to stress the CPU heavily, generating more heat that most realistic loads. Two instances are used to ensure that both cores are stressed.
  • Throttlewatch 2.01, used to monitor the throttling feature of the CPU to determine when overheating occurs.

Sound pressure level (SPL) measurements were made with the fan powered from the lab variable DC power supply with no other noise sources in the room. The ambient conditions during testing were 18 dBA and 22°C.

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. The fan was tested at four voltages: 5V, 7V, 9V, and 12V, representing a full cross-section of the its airflow and noise performance.


The Fan: The first portion of the table below shows mostly information provided by Spire. The yellow portion of the table displays the results of our testing.

Stock Fan Profile: Spire Fourier IV
Brand Fanner Tech Power Rating 2.4 - 4.8W
Manufacturer Shen Zhen Airflow Rating 36.8 - 58.21 CFM
Model Number FD09025B1M RPM Rating 2000 - 3500 RPM +/-10%
Bearing Type Ball Noise Rating 19.0 - 26.0 dBA
Hub (measured) 1.29" diameter Header Type 3-pin
Frame Size 92 x 92 x 25 mm Starting Voltage 3.9V
Our test findings
3300 RPM
75 CFM
2650 RPM
62 CFM
2150 RPM
49 CFM
1530 RPM
35 CFM
With supplied Fan Speed Controller
Max (11.8V)
3250 RPM
74 CFM
Mid (6.8V)
2000 RPM
46 CFM
Min (4.6V)
1400 RPM
31 CFM
The fan was measured in free air without load as per our standard fan testing procedure.

The SPL measurements should make it very clear that this is not a quiet fan except at the very lowest settings. The "M" for medium speed seems like a bad case of mislabelling. In our books, this is undoubtedly a high speed, high power fan. Both the ball bearings as well as the clear plastic construction had audible consequences. It was only at the 5V or minimum controller settings that the acoustic signature became benign and quiet enough for the fan to be considered worthy of use in any of SPCR's own computers. As the 2000 rpm or 7V mark was approached, the noise simply became too much to be acceptable. It was not just a matter of the overall level or "quantity" of noise; its quality was plainly annoying. The recording further below will clarify better than words.

Cooling and Noise

Spire Fourier IV with Stock fan
Fan Voltage
°C Rise
Spire Fourier IV with Reference 92mm fan
Load Temp: CPUBurn for ~20 mins.
°C Rise: Temperature rise above ambient (22°C) at load.
°C/W: Temperature rise over ambient per Watt of CPU heat, based on the amount of heat dissipated by the CPU (measured 78W).
Noise: SPL measured in [email protected] distance with high accuracy B & K SLM

Stock Fan @ 12V: The quick-eyed reader will notice the 5 [email protected] measured SPL increase in the cooling / noise table above compared to the the fan table in the previous section. It is not an error. (It's there through the entire speed range.) The increased turbulence of the fan mounted on the heatsink made it much louder than in our standard fan test setup. There was also transfer of vibration into the heatsink, which added its own tonal sounds to the mix. Naturally, it was far too loud. There was also an odd variability in pitch as if the fan was changing speed, up and down. This was not the result of interaction with our power source; the voltage across the fan terminals was steady. The cooling performance was good but not top notch.

Stock Fan @ 9V: The noise level dropped quite a bit. Subjectively, it seemed only about half as loud as before, but still much too loud. At this speed, too, the fan was louder operating on the heatsink than when it was in free air. Cooling performance was barely affected, which suggests that the airflow at 12V is ineffectively high.

Stock Fan @ 7V: The stock combination finally approached our threshold of quiet, 30 [email protected] The overall sound quality was not good, however, with traces of resonance and vibration as well as tonal characteristic audible through the turbulence noise. Cooling performance dropped 2°C, to a 25°C rise above ambient, but we'd still consider this pretty good performance.

Stock Fan @ 5V + Controller at Min: Finally, the noise level dropped into acceptable territory. It should be quiet enough for most users here, as long as the quality of the sound is acceptable. Since there are still some tonal aspects to the sound, users reactions will probably vary. Cooling performance fell into the barely acceptable range, however. Setting the controller to the minimum setting brought noise down a titch and CPU temperature up a notch.

Reference fan @12V: What a relief to switch to this fan! As we've remarked elsewhere, the reference fan may be quiet enough at 12V for most people. It seems very slightly louder than in free air, due to increased turbulence through the fins. The cooling performance was actually the same with the stock fan and its controller at minimum, but it was smoother and quieter.

Unfortunately, the cooling performance with the reference fan at 9V and below fell into the unacceptable category with ourCPU. If we assume case temperature to be 10°C higher, we'd be seeing CPU temperatures of 67°C and more. That's not recommended. On the other hand, if your processor is one rated for lower power disspation than the test rig's fairly hot Pentium D950, the Fourier IV could be good enough even with the Nexus at 9V.


To find a heastink/fan of comparable size, we have to go back quite a ways. Our recent reviews have all been of large heatsinks. Here's a possible list:

Zalman 8000: It was tested a year ago on a different platform with a cooler CPU, and we thought it was a stinker, terrible value for money. The only thing better about it is the better installation system. Currently in the market for around the same price as the Fourier IV, which I'd take over the 8000.

nMedia Icetank: Again, tested a year ago on a different platform with a cooler CPU, but it was a decent performer with a decent fan. Guesstimating puts is performance on par with the Fourier IV, and it came with a better fan. Also has a simple clip mounting system. Similarly priced. We think the F-IV loses out here.

Zalman 7700 / 7000: These go back 2-3 years, but they're still on the market, they are good performers, and they may be viable alternatives with today's CPUs. I would personally take them over the F-IV on the hassles of the F-IV's installation system alone.


Spire Fourier IV with stock fan: 4.6V-5V-7V-9V-12V, with 5s ambient between levels: One Meter (1mb file!)
The first 4.6V level is with the fancontroller set to minimum.
Recordings at one foot were not made; you can hear clearly that it's too loud with the one meter recording.

(Our current databse of HSF recordings done the same way is a bit small.)

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

Zalman 8000 w/ stock fan: 5V-7V-9V-12V, 5s Ambient between levels: One Meter, One Foot

Nexus 92mm fan: 5V-7V-9V-12V, 5s Ambient between levels: One Meter, One Foot


These recordings were made with a high resolution, studio quality, digital recording system and are intended to represent a quick snapshot of what we heard during the review. Two recordings of each noise level were made, one from a distance of one meter, and another from one foot (30cm) away.

The one meter recording is intended to give you an idea of how the subject of this review sound in actual use — one meter is a reasonable typical distance between a computer or computer component and your ear. The recording contains stretches of ambient noise that you can use to judge the relative loudness of the subject. For best results, set your volume control so that the ambient noise is just barely audible. Be aware that very quiet subjects may not be audible — if we couldn't hear it from one meter, chances are we couldn't record it either!

The one foot recording is designed to bring out the fine details of the noise. Use this recording with caution! Although more detailed, it may not represent how the subject sounds in actual use. It is best to listen to this recording after you have listened to the one meter recording.

More details about how we make these recordings can be found in our article: Audio Recording Methods Revised.


Some products are difficult to stay neutral about. The Fourier IV looks so promising, with a nice set of features and technology. Yet it caused much frustration over installation and acoustics. While the heatsink cools quite well with the supplied fan, the cost is a level of noise rarely encountered at SPCR. It's much quieter when the fan controller is turned right down, but then the cooling becomes questionable. It's obviously not intended for good cooling performance and low noise.

There is the possibility that the heatsink was not making optimal contact with the CPU, but this is a problem that could afflict any user. We were unwilling to find out, because it meant risking the test platform motherboard by possibly overtightening the mounting screws.

The installation issues are of concern to everyone, not just silencers. Poorly designed mounting systems are not uncommon, but it's a shame to see one even in such a heavy heatsink with high end aspirations. A little bit of ergonomic thinking could have made a big difference here. Finally, the current market pricing puts this model at a disadvantage against many better designed, better performing, and quieter HSF that we've already reviewed.

It's difficult to recommend this HSF to anyone outside the circle of fanatical heatsink collectors who must try everything interesting in the market. It may be OK for the gamer with a tight case who doesn't care about noise, but for most others, there are better options whether your priority is cooling performance or low noise.


* Good cooling performance
* Nice size
* Very secure when installed
* Nice fan controller
* Amazingly powerful fan

* Poor installation ergonomics could lead to damage of motherboard
* Horribly loud fan
* A bit too heavy
* Cooling not good enough for the noise
* Tendency toward tonal resonances

Much thanks to Spire for the Fourier IV sample.

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Articles of Related Interest

Recommended Heatsinks
SPCR's unique heatsink testing methodology
SPCR's standard fan testing methodology
Zalman 8000
nMedia Icetank
Zalman 7700 / 7000

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