blowers vs fans

Rasterman · Post by **Rasterman** » Tue Dec 26, 2006 5:34 pm

Has SPCR looked at blowers vs fans? I did a search but didn't find any discussion on it. I have read the blowers are more efficient than fans. Perhaps they would yeild lower RPMs and less noise than a standard fan at the same CFM?

spookmineer · Post by **spookmineer** » Tue Dec 26, 2006 5:43 pm

By blowers do you mean centrifugal "fans" as opposed to the more usual axial fans? These are noisier then axial fans for the same amount of CFM.
They are used when there is a need for a high(er) static/dynamic pressure (for example leaf blowers), which (according to other threads here) is not really needed in PC's.

pcy · Post by **pcy** » Wed Dec 27, 2006 3:04 am

Hi,

Yes... I too am unclear about this distinction between a blower and a fan.

However, the CPU fan is being used to push air through the CPU heatsink, which is in fact a pretty substantial obstacle to airflow. The actual airflow is way down on the free flow CFM the maufacturere would quote; and the fan is working hard to produce the requisite pressure.

Maybe this is one plcae where a "blower" might work more efficiently and end up producing less noise?

Peter

jaganath · Post by **jaganath** » Wed Dec 27, 2006 4:12 am

I too am unclear about this distinction between a blower and a fan.

Basically fans are axial and blowers are either centrifugal or tangential:

http://www.cooltron.com/technical_ChooseFan.shtml

Maybe this is one place where a "blower" might work more efficiently and end up producing less noise?

In terms of pressure delivery, centrifugal fans are best, then cross-flow/tangential fans, axial fans being the worst. So on first inspection axial fans look like the worst choice for a heatsink application. But centrifugal fans are very noisy, and the few cross-flow fans that are available to the PC cooling market aren't very good, eg.:

Cross-flow fan review

That, and the fact that the market for axial fans is huge and individual units are cheap explains the dominance of axial fans for heatsink cooling (although you will notice that many high end graphics cards use a slot [centrifugal] fan).

So in theory a blower or cross-flow fan ought to be more efficient and quieter, but in practice this is not often the case.

http://www.hardcoreware.net/reviews/review-213-3.htm

the Coolermaster Jet ...the one major drawback of this cooler, aside from its weight, is the fact that when the fan is running at full speed, it actually does sound like you have a jet engine inside your case. If you are one of those people that think the Aeroflow is loud then you will not like how this thing sounds when ramped up. The good news though is that even after using the fan controller to lower the fan down to a reasonable level (ie. that of the Aeroflow) I was still able to maintain temperatures that were only 2-3C off from what I attained at the highest fan speed.
fan speeds can be adjusted from 1900rpm to 3500rpm and anything in between. At 1900 rpm the cooler was almost silent. At 3500 rpm it sounds like you have a blow dryer running at high speed inside your PC.

So obviously there are some manufacturers who are trying to realise the theoretical benefits of a non-axial design.

pcy · Post by **pcy** » Wed Dec 27, 2006 4:24 am

Hi,

Very helpful - thanks.

Peter

Felger Carbon · Post by **Felger Carbon** » Wed Dec 27, 2006 5:32 am

Frosty Tech recently posted a review of a Thermalfly cooler with a centrifugal blower. The K8 results on page 4 showed that, with the blower turned down, it out-cooled a Zalman 7000B-Cu while being 9.5dBA quieter!

Chris Chan · Post by **Chris Chan** » Wed Dec 27, 2006 7:28 am

Interesting, FC! So it all depends upon the design of the cooler. Looking at that ThermalFly cooler, looks designed specially for that blower. But we need to keep in mind that Zalman coolers are not known for SPCR low noise standards in stock form.

pcy · Post by **pcy** » Wed Dec 27, 2006 7:57 am

HI,

And a Zlman 7000 scarcely qualifies a heavy competition.

Peter