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What's the SLOWEST possible fan speed?

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June 1, 2010 8:14:56 AM

I'd like to add a fun touch to my case by using one of the fans as decoration rather than cooling. I'm thinking maybe swap out the fan blade for a spiral-y design, etc. Does anyone know if it's possible to slow down the fan to a speed where you could actually see the thing spinning rather than it being just a blur? What would be the best method for slowing it down as far as it can possibly go?

More about : slowest fan speed

a c 190 K Overclocking
June 1, 2010 8:17:50 AM

Variable resistor in the powerline on the fan imo,
Or buy a Fan controller which is a set of V.R's in a nice shiny mounted panel you hook several fans to.
Moto
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June 1, 2010 8:25:52 AM

I thought of the fan controllers, but I was worried that they might not go as low as I'd like. I mean, I assume that there's a limit to how slow they'll make the fan go, right? The manufacturer is still expecting that you want to push air with the thing (which I don't!) :) 

Will adding my own resistors to the powerline of the fan put any sort of undue stress on my power supply?
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a c 190 K Overclocking
June 1, 2010 8:41:21 AM

Resistors are designed to lower the current getting through, Its what they do :) 

on your psu theres a label saying how much power is delivered to each line, I'd find the one with the lowest number so your 'taking' a low draw of power to begin with, less for the resistor to cope with.
You would have to look up your fans current draw, should be on the label on it somewhere, I think mine are about 0.12A on 12v, fans dont need a lot of power
but if you take your fan to a hardware/electrical shop and explain what your after doing, they should be able to give you the correct resistor for your needs.
but no, it shouldnt put undue stress on the psu, the psu delivers what power you ask it for.
Moto
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a b K Overclocking
June 1, 2010 4:38:40 PM

Keep in mind that fans do have a minimum required amount of current to start them from standby. They normally list such in the specifications.

Adding resistors will lower the current getting to the fan, but without reaching the fans minimum the fan will just sit idle.

Look for a fan that has a very low maximum speed and then look for the required starting current. Something like this might slow it down a great deal but perhaps not quite enough.

another thought: if you just want a spinning design then you don't really need to buy a "fan." you could just buy a small electric motor to accomplish the same thing. Many of these can also run at the very low speeds that you would want.
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June 1, 2010 6:52:29 PM

Thanks for the input so far! I love tomshardware!

I found a fan with 500 RPM on newegg:
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

I have no idea what 500 RPM looks like when it spins, but I think it's the slowest out there. Actually kind of funny that it exists...it moves almost no air at all. According to Scythe's website, it takes only .07 amps. I wonder if that could be brought down even lower. The online specs don't indicate a minimum current to start from standby, but maybe it's written on the packaging? (if it comes with packaging, that is...)


I like the idea of just doing a motor (as long as it's not too loud...), but I've never done anything with electronics or soldering before. I went with the fan idea because the plug's already wired, and because I know fans are built to be fairly quiet. I'm interested in trying just a plain old motor, but what kind of stores sell them? And how would I attach it to my power supply?

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a b K Overclocking
June 1, 2010 8:30:21 PM

It looks like 500rpm is the minimum for the fan you selected. There is another on their website which might suit your needs better. Here is an excerpt:

Scythe
Slip Stream 120 PWM Case Fan

The popular Slip Stream Series will be expanded with a further variant of PWM fans. New Slip Stream PWM 120 mm fan can work by using a PWM enabled motherboards, which are automatically controlled. Fan speed range begins by 0 (+200rpm) goes up to 1,300 rpm (±10%) and air flow is up to 74,25 CFM = 126 m³/h produced.

To answer your question, 500rpm would still blur. I'm not familiar with small electric motors myself. I know places like digi-key sells that sort of equipment, but i'm sure there are local stores in your area. As long as the output voltage/amperage of your psu plug is within the motors range you should be fine. Just remember you need a DC motor not an AC.

All things considered, a fan is the easier option but will most likely spin faster. A motor would have the speed you want but it will require more research and time on your part.

Happy hunting.


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June 3, 2010 7:23:34 PM

Best answer selected by uglymonkeybutt.
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