PAPST Fans (Silent PC Part 2) 14th December 2002
PAPST are a company that many will not have heard of although they are highly renowned in their niche market of manufacturing fans and air conditioning equipment. Based in Europe they ship all over the world to mainly the construction industry and their fans are used in office blocks everywhere. Now with an extensive range of 12V DC fans they have suddenly become of interest to the PC cooling industry.
While this is a review of PAPST fans it is also the second in our series of articles in making PCs as quiet as possible in operation (the first was our PaxMate acoustic matting installation guide). We have the following fans from PAPST:
All are the standard 25mm thickness except the first one which is 15mm thick. The test system was as follows:
The other components aren't of too much relevance for the purposes of this test. Also for this test we removed the chipset fan although this caused the system to lock up during heavy use. Don't do this at home unless you are going to put a hefty passive heat-sink in its place.
For comparison we will be interchanging the 4 case fans with Sunon and PanaFlo ones. We will also be using 60mm YSTech, Sunon and PanaFlo fans on the CPU heat-sink. We won't even bother comparing with any Delta fans as our goal is peace and quiet rather than performance.
We started by testing each fan on a 12V power supply with the current regulated to comply with the specifications of the fan. As expected the Sunon fans and the YSTech ones were about the same volume. The PanaFlo were quieter but the PAPST were virtually silent in terms of airflow noise. One thing we did notice about the PAPST fans was a faint mechanical noise (like a very rapid clicking). This was puzzling until we listened to the PanaFlo ones again carefully and noticed it too although it was drowned out by the airflow noise. It appears that the PAPST fans are so quiet we can hear the mechanism in action. This noise will probably be substantially reduced once the fans are "broken in" over a period of a few weeks.
Testing singly in the open air is one thing but things change when we look at the overall effect of several fans together inside a case. The laws of aerodynamics tell us that it is better to have a surplus pressure inside a case than a negative pressure. In the latter case we get a vacuum effect which sounds (depending on the degree of negative pressure) like a vacuum cleaner sucking. Case designs do not help in this regard as there are usually more fans blowing air out of a case than blowing in (PSU plus 2 extractor fans versus usually one or two inputs at the front of the case). Our test system has holders for 4 case fans (2 in and 2 out) but we can minimize the PSU effect by turning its fans down to minimum with the dial on the back of the PSU.
When using all Sunon fans we got a substantial vacuum effect and the noise was not too bad because it was even. The high pitched noises were filtered out by our acoustic matting and the fact that our drives were enclosed in Molex Silent Drive housings (Review upcoming). This was perfectly bearable over a period of time but I would not sleep in a room with that much noise (having sensitive hearing).
Switching to all PanaFlo fans the volume was much lower with virtually no high pitched noises and less airflow noise although at the cost of reduced airflow. This is the same setup we normally use in this system and many people have slept in the same room as this system with it going all night (no bragging - it's just a very popular room). Most people will be perfectly happy with this amount of noise.
Finally we switched to all PAPST fans (the 120mm one will be tested at a future time when we have received an aluminum case from Cooler Master that takes it). The noise reduction was dramatic and is a testament to the engineering design and manufacturing process that went into its construction. From a distance the only way we could be sure the PC was on was from observing the power LED on the front of the case.
We also tested the thin 60mm fan in our SKY+ PVR (personal video recorder) and there was no noise at all with the fan on constantly. As more and more hard disk based recorders and other peripherals become common place in the home greater thought will go into noise considerations. The fan in my Epson Color 980 is quite irritating when it occasionally comes on.
For a more scientific analysis we could have used fluid dynamics to explain our observations but there are just too many separate factors to take into consideration and most equations only work with laminar flow. This is great if we're blowing air down a tube or a straw but PC cases are very complex to model mathematically. Fortunately the observations above were borne out by no less than 8 people and should be quite accurate.
We have reached another mile-stone in our quest for the silent PC. PAPST have brought us the quietest fans yet, although at a price premium and a performance penalty. I hesitated to add the latter because PAPST have a very wide range of fans and there are some high performance ones which still have lower rated noise figures than most "silent fans". There is no doubt these fans should be used whenever less noise is an overriding concern and performance is not critical. The performance issue can be offset to a point by using larger and more efficient heat-sinks. We can say with confidence that the success of PAPST is assured by the PC market segment alone. Are these the best fans in the World? Probably.
We would like to thank PAPST for the review sample fans.
If you are a reseller of fans and would like to sell PAPST fans in the UK (or anywhere in the world for that matter) mail us your details here and we'll pass them on to the appropriate person at PAPST.
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