Sytrin KuFormula VF1 Plus graphics card cooler

Cooling
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FAN

The cross-flow fan is highly unusual, and deserves a mini-review of its own. Unlike most typical axial fans used in computers, it is made completely of metal, and it weighs considerably more. It comes with its own bracket, so the additional weight does not have to hang from the graphics card. Noise seems to have been taken into account, as all of the moving parts (motor included) are isolated from the frame with soft rubber.


Air is sucked in through the opening at the top and forced out through the rectangular vent at the bottom.


A good view of the intake and the fan blades.

Unfortunately, the fan vibrates at lot, even at lower speeds and the rubber decoupling is not that effective against this vibration. Perhaps the relatively high mass of the metal blades makes it more difficult to balance than a plastic axial fan.


The motor is decoupled with soft rubber...


...and so is the axle at the other end.

The bracket is quite substantial, and should not have any problem supporting the weight of the fan. The bracket comes in two parts: The bracket itself, and a mounting plate for the fan. The two parts and the fan are screwed together with machine screws, and can be assembled easily outside of the PC.

The bracket also comes with a simple fan controller that allows the user to switch between three preset speeds. The controller is powered by a standard Molex plug and accepts 12V as its input voltage.


A weighty bracket for a weighty fan.


Three speed fan control.

FAN NOISE

The fan was placed on soft cushioning foam and driven by a variable DC voltage power supply. We listened and measured the noise with our B&K 2206 sound level meter (SLM) from one meter away. The fan's airflow was pointed away from the SLM. It was measured both in free air (unmounted SPL) and installed on the heatsink (mounted column). The supplied fan controller was used except for the 5V test, where the fan was connected directly to our power supply.

Sytrin KuFormula VF1 Plus Cross Flow Fan
Fan Controller
Voltage
Rated Speed
Unmounted SPL
Mounted SPL
H
11.8V
3150 RPM
41 dBA@1m
42 dBA@1m
M
9.5V
2400 RPM
37 dBA@1m
38 dBA@1m
L
6.5V
1550 RPM
25 dBA@1m
26 dBA@1m
bypassed
5V
20 dBA@1m
20 dBA@1m

The three preset fan speeds delivered 6.5V, 9.5V, and 11.8V to the fan. Only the lowest speed could be considered quiet, and even that had an unpleasant noise character that would be out of place in a quiet system. The fan started reliably at 5V, though, and was considerably quieter than the lowest preset speed.

All of the preset fan speeds had very rough, "dirty" noise signatures. The dominant noise was always the hum of the motor, but a sizable amount of clicking and rattling could be heard underneath. At the medium and high settings, turbulence noise was also a factor. However, the sheer volume of noise at these levels makes the subjective description less relevant; both high and medium are too loud, whatever the quality of noise. The lowest setting was marked by a distinct pure tone that was decidedly unpleasant to listen to. The tone had a very slight warble that called attention to itself.

At 5 volts, the hum of the motor noise disappeared almost entirely, replaced by a chattery chugging that made us wonder how well balanced the fan was. A faint secondary tone could also be heard, and this one did not warble or change in any way. At this level, the fan was quiet enough for most systems, and would probably blend in to the other noise sources in the system. However, it is still clearly audible, and would not be suitable for use in a system that is meant to be inaudible.

In addition to the changes with fan speed, the noise also changed significantly when the heatsink was placed in front of it. The resulting impedance (to airflow) caused the noise level to increase noticeably and measurably, as the table above shows. The most noticeable changes were:

  • motor hum rose to a higher pitch
  • increased broadband turbulence noise


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