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Old 02-04-2009, 08:06 PM
Jason Jason is offline
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Join Date: Jan 2003
Location: Orlando
Posts: 1,216
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We get lots of mail at TechwareLabs, most of it is spam. every now and then a nugget of real qualified mail squeezes through the gaps. See if anyone out there can assist this fan across the globe with his problem:

Hello Jason,

I read your review and efforts to give information about the Aerocool
Gatewatch 2 lately.
After I have purchased it, unfortunately ... Now I think I 'might' have a
problem, which I would love to solve, with your advice (if possible).
As you know, the gatewatch has 4 channels to plug in fans. Though ... I have
"more" fans to connect to it.
For the cpu I am using two 120 mm fans which both deliver a RPM of 2000.
I would like them both to be connected to the same CPU fan channel of the
Gatewatch 2
Also it would be good to know .... (as you stated in your review) actual
vary fan speed 700 - 1000 RPM (is this the maximum I can get out of "any"
fan ? or should I "presume " (in my case 1000 RPM read on the LCD screen ,
in fact "could-would" mean 2000 RPM on my fans ?
I think you need some extra info to give a serious answer ...
Here are the fans I use
CoolerMaster R4-L2R-20AC-GP
technical :
- 120 mm fan
- speed 2000 RPM
- Volts : 12 VDC
- INPUT (Watt) 4.2 W +/- 10 %
- Current (Ampère) 0.35 A +/- 10%
I also read on the manual of the Gatewatch, each channel is designed to take
0.5 A
So I guess I have a problem about the Ampères when I will put both fans onto
one channel right ?
I have eaten nothing about "electronics". (unfortunately), the reason for my
quest. Though I know how to solder, open and put all back together :-), So I
guess, this puts me, (more or less) in a situation you were in some (a long)
time ago. I sure would love to know more about it, but I am colourblind on 3
colors (brown, green and red). So I had to study something else, or I would
fry a lot of people's their blenders.
Can you tell me, what component I should replace within the Gatewatch (to a
stronger one), so I can trigger both fans on ONE channel.
Eventually, must I change something else ? Or look into something else ?
I will be more then pleased with any answer you provide me. To put me in the
correct direction.
Thanks for your time and efforts. Keep up the good work on techwarelabs,
your reviews are always "to the point" ;-)
Kindly yours,
a "fan" from Belgium
John Stylemans
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Old 02-04-2009, 11:11 PM
JackW JackW is offline
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Join Date: May 2008
Posts: 1,040

Originally Posted by Jason View Post
- Volts : 12 VDC
- INPUT (Watt) 4.2 W +/- 10 %
- Current (Ampère) 0.35 A +/- 10%
I also read on the manual of the Gatewatch, each channel is designed to take
0.5 A
So I guess I have a problem about the Ampères when I will put both fans onto
one channel right ?
Not totally that simple. If the fans are in series then they will both get the full .5 Amperes, however if they are in parallel they will split it among them following a formula called a current divider (if the fans are the same it splits evenly). You'll have to see how your fans will connect (look at the pictures here:

Thing is though, if the current is the same, then the voltage will have to be divided over the two fans and the 2nd fan will be weak in comparison to the others. You'll also have to make sure there is enough wattage of power to run the fans, power = current * voltage. Whether its series or parallel you will lose out. Computers typically are organized in a parallel manner in regards to connecting components.

I suspect that the reason they suggest only one fan is that someone who is familiar with the system sat down with it and did the calculations. I'm not at all familiar with the device or any of that, I'm just a computer engineer so I get taught all of this. Get a multimeter and try to figure out why its not working.

By inspection I suspect there will be 2 amps that gets divided over the 4 rails that should allow you to connect 5.7 fans to, but what you'll probably have to do is connect all of the leads and then make your own divider circuit. This has problems, namely can the cables take 2 amps. Honestly there is probably no easy solution from what I've been taught, but I'm not an expert on the system.


Note: Sticky'ed so it doesn't get lost off the first page.
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Old 02-05-2009, 11:11 AM
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R4D10Active R4D10Active is offline
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I haven't had the oppourtunity (yet) to take one of these apart but from the looks of it I would think that modifying this to run both fans off of a single channel might be difficult. I would think that replacing components might pose another problem as I would guess quite a few of these components are surface mounted and when you start changing out components you tend to damage the board (if you don't have surface mount soldering experience) and who knows if the new amperage you are drawing won't damage the traces on the board itself. I wish I had an answer for you of how to accomplish this but until I can find one of these to disect and do the mod myself I am weary of giving any information which might cause you to destroy your equipment.

Bad advice can be the harbinger of death for electronics....

That which is to emit light must first endure the flame.

"The 'C' students run the world" - Harry S. Truman
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