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Graphics cards, Fan currents

Last response: in Graphics & Displays
July 8, 2011 10:12:36 PM

Greetings, I have an MSI GTX470 Twin Frozr card that I am gonna "convert" to watercooling. My plan is to give the graphics card control of one of the 120mm fans thats attached to the radiator for cooling the card. I know the 120mm fan must be a 4pin PWM, or atleast thats what i'm assuming (fan controller is on card somewhere). Is there anyway I can find out what the current draw of the 2 fans that are on the card currently? they are only 80mm fans so I am guessing max 1A but probably less. I dont want to blow up the fan controller on the card testing different fans so an accurate answer would be appricated.

Anyone ever opened one of these cards up btw?
a b U Graphics card
July 9, 2011 7:21:47 AM

There's a safer way of doing that, which basically is powering the fan or fans from the mobo or molex PSU and controlling speed from card.
4 wires from fan split; two to power and two to card.
Think about it and you'll see what I mean.
Pin 1 ground black
Pin 2 12v yellow
Pin 3 sensor green
Pin 4 control blue

Edit; This is a 3 wire example, cant find correct one;

Edit2; Can anybody verify that the above will work.
July 9, 2011 10:25:50 AM

Thanks Jeepster50, most helpful and I see what you mean. If I connect the power of the fan to the molex can i still regulate fan speed if i connect the sensor pin and control pin from the gcard? Mobo only has sense on SYSFAN1, both mobo fan points produce +12V, is it 0-12V or something like 5V-12V?
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a b U Graphics card
July 9, 2011 10:35:19 AM

I've 2nd thoughts on whether that will work or not. Slept on it and now I'm not so sure it will work. let me do some checking & get back to ya.
July 9, 2011 10:48:46 AM

Still waiting on MSI to get back to me too Jeepster so don't stress yourself :D  although I really doubt MSI will give me the info I'm looking for. This will probably end up being trial and error
a b U Graphics card
July 9, 2011 11:18:28 AM

The way I read this it should work!
" Fan Speed Response to PWM Control Input Signal
The PWM input shall be delivered to the fan through the control signal on Pin 4 (see Section 2.4).
Fan speed response to this signal shall be a continuous and monotonic function of the duty cycle
of the signal, from 100% to the minimum specified RPM. The fan RPM (as a percentage of
maximum RPM) should match the PWM duty cycle within ±10%. If no control signal is present
the fan shall operate at maximum RPM. See Figure 2."

Edit; For more than one fan you need a cable arrangement like one pictured in post #117 of this thread; Its made by Rosewill