40mm fans w/auto temperature control

Control: management of fans, temp/rpm monitoring via soft/hardware

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silence_seeker
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Joined: Sat Oct 22, 2005 12:12 pm

40mm fans w/auto temperature control

Post by silence_seeker » Sun Oct 24, 2010 11:53 pm

An external hard drive enclosure of mine came with two (relatively noisy in my opinion) 40mm fans which blast at full speed all the time. I find this unnecessary and would like to have their speeds adjust automatically according to the temperature inside the enclosure.

I've seen 120mm fans with built-in temperature sensors (or temperature sensors connected to a wire to the fan), but are there 40mm fans like this to be found?
The fans should be 12V and have 3 pins.
Last edited by silence_seeker on Thu Oct 28, 2010 1:15 pm, edited 1 time in total.

wouterr5
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Location: The Netherlands

Re: 40mm fans w/auto temperature control

Post by wouterr5 » Wed Oct 27, 2010 10:02 am

For a product that probably doesn't consume more than 6 watts at idle, 2 fans at full blast sound a bit overkill indeed - slowing them down would be the appropiate thing to do.

The thing is, some people strongly advise against temperature-regulated cooling, such as this guy on Anandtech:
The OP is nominally correct. While I wouldn't go so far as to say "NEVER use an on-demand cooling system", I'd say they're likely to do more harm than good unless carefully engineered and integrated with the HDD.

Rapid changes in temperature can kill a drive faster than elevated temps due to, e.g., thermal expansion/contraction of components (heads, platters, spindles, etc.), and air density changes which affect head ride height.

Those changes require active adjustment and compensation, and are necessary and common in today's drives/controllers. However, there are limits. Drive manufacturers specify a maximum temp change/time (even if it may not show in the data sheets available on their web site).

The best solution is to maintain a steady and moderate temperature change. The worst solution is a typical/cheap "bang-bang" controller that starts/stops when temperature limts are reached, and which causes rapid changes in the drive's temperature.

Case in point: The absolute worst thing you can do for your laptop drive after leaving it in the car for hours on a frigid day is drag it into a warm room and immediately start pounding on it. Virtually guaranteed to result in errors and reduced life (if not short-term failure).*

In short, active cooling is not necessarily bad, but stupid active cooling that causes wide temp swings over short periods in the drive can cause far worse problems than allowing the drive to run at an elevated and slowly changing temp.

This has been a problem for many years, and increasingly as tolerances decrease (especially with higher track densities). While drives/controllers continue to adapt and improve, it's still a significant factor, and the larger the media the worse the problem. For recent papers (sorry, don't have any recent freely available links), see:

http://scitation.aip.org/getabs/servlet ... yes&ref=no

http://ieeexplore.ieee.org/Xplore/login ... ision=-203

* Yes, people talk about the "freeze your HDD" to try and recover it. (It may even work--never tried it.) But subjecting an HDD to that kind of rapid temperature change abuse even occassionally is guaranteed to kill it in short order.
But, regarding your question, I don't know of any fans with temperature sensors outside of the stock AMD coolers, which are 70/80mm.

KayDat
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Location: Melbourne, Victoria, Australia

Re: 40mm fans w/auto temperature control

Post by KayDat » Wed Oct 27, 2010 7:05 pm

Arctic cooling have temp controlled fans, but they come in standard PC 80/92/120 sizes. I think you're out of luck in terms of 40mm fans, unfortunately.

silence_seeker
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Joined: Sat Oct 22, 2005 12:12 pm

Re: 40mm fans w/auto temperature control

Post by silence_seeker » Thu Oct 28, 2010 2:05 pm

Hmmmm.... :?
The hard drive enclosure (Proavio S4UF 4x removable bay rack) comes with 2x 40mm cooling fans which are connected to a "temperature monitoring" board.
The circuitry on that board disappointingly does not control the fans but detects that they're both connected, and via two temperature sensors located at different places inside the enclosure, monitors that the hard drives don't reach too high ambient temperatures. If the temperature goes above a certain preset threshold level (45, 55 or 75 C) or one/both of the fans stop spinning the alarm beeps along with a flashing LED on the front panel of the enclosure indicating that something is wrong.

Since the fans both get a constant 12V, would it be possible to insert a temperature sensing circuit between each fan and the 12V power connectors on the "temperature monitor" board so that their speeds adjust according to the enclosure's internal temperature, in addition to the existing "temperature monitoring" board?

From what I've heard, that 3rd pin from the fan sends out a "pulse detect" signal, indicating that "yes, I'm alive", or lacking that signal alerts that the fan is dead/malfunctioning. I'm guessing that I could keep that wire connected as it already is to the "temperature monitoring" board and also make sure that the additional fan controlling circuitry never turns the fan off completely but instead adjusts the fan speed from spinning slowly to full speed (and anything in between) effectively avoiding any "fan malfunction" alarm/flashing LED. A fan that spins slower/faster (as opposed to off/full speed) would also address the issues quoted by wouterr5, above.

So the question is if such circuitry is readily available and if it would work like I've described it here?

lodestar
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Re: 40mm fans w/auto temperature control

Post by lodestar » Thu Oct 28, 2010 5:31 pm

KayDat wrote:Arctic cooling have temp controlled fans, but they come in standard PC 80/92/120 sizes. I think you're out of luck in terms of 40mm fans, unfortunately.
Arctic Cooling do in fact have a temperature controlled 40mm fan, but they don't sell it separately, only as part of the HC 01-TC. The 40mm fan that comes with HC 01-TC has a range of 1,600 to 4,600 RPM. See http://www.arctic-cooling.com/catalog/p ... 9_&mID=605.

KayDat
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Location: Melbourne, Victoria, Australia

Re: 40mm fans w/auto temperature control

Post by KayDat » Thu Oct 28, 2010 6:04 pm

Well, I stand corrected. You can always contact AC and ask if you can buy the 40mm fan as a spare part. AC themselves sell a whole range of spare parts already, such as CPU/GPU cooler fans, RAM sinks etc.

silence_seeker
Posts: 51
Joined: Sat Oct 22, 2005 12:12 pm

Re: 40mm fans w/auto temperature control

Post by silence_seeker » Sat Oct 30, 2010 5:27 am

That's good news if they can sell those fans separately.
In the meantime I came across a temperature sensing fan speed control circuit at eBay. Would two of those (one for each fan) do the trick of regulating the fan speeds (and keeping the noise level down)?

My only concern is how the hard drive enclosure's circuit uses the fans' 3rd pin -if it assumes fan failure whenever fan speed is below full speed or if it assumes everything is OK as long as the fans spin at all, at any speed. I should probably just connect a resistor between one of the fan's voltage pins (to lower the fan speed) and see what happens.

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