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Possible workaround when something like speedfan wont work...?

post #1 of 5
Thread Starter 
Hey All,

This is mostly for laptops, but can work for desktops too...

I found this link about 4 wire and 3 wire discussion:
http://www.overclock.net/air-cooling/744476-3-wire-vs-4-wire-fan.html

The 4 wires for the laptop are as follows:
**Ground. (-)
**12v. (+)
**RPM Signal.
**Fan controller speed.

idk if the order is correct, but I read that configuration is the most likley for the 4 wire fan setup...

I have been looking at the signal wire controller and it appears to just be a PWM signal "OUT", from the fan.
And a PWM signal "IN", to the MotherBoard which has PWN controlled resistance for fan speed control.

So, if thats the case, if I tweek my connector and disconnect the PWM signal out from the fan and stop it from getting to the board, the fan should run at MAX speed...?

What do you think about trying this?
Do you think there is possibility of damaging a motherboard like this?
All I'm doing is removing the one wire...

**I did think of fan overspin and exploding, but its made to run at 5x, then I'll run it there, it breaks, I'll just buy another one...lol
If it does work, I'm adding an aluminum shielding to contain the fan better just-in-case smile.gif

I'm going to try this on my G72gx in short intervols to keep heat low, but just to test if this actually works. biggrin.gif

If so, I'm adding a flat switch underneath for MAX fan when gaming biggrin.gif
because most of the time the fan can run at 1 or 2 times faster than the 3rd speed and if its always that fast, this meens better temps and clocks smile.gif
post #2 of 5
If you remove the PWM signal, the fan will operate 100% full speed.

For reference, a standard PWM fan cable and wiring diagram here

post #3 of 5
Thread Starter 
thanks,

I already had a pin reference for my motherboard...
(However it took 4 hours to find it...lol).

I wanted to ask because with some computers and electronics, I remembered boards going bad simply because the fan messed through the PWM signal line...

I also asked because:
Most PWM signals I worked with are outputs and I didn't want to cut a wire in my 2,000 laptop just to find out it was an oops...lol

But in any case, I soldered an on/off switch for my fans PWM and I can have full 5,000 RPM constant or auto speed...

I did however (before I added the switch), connect a meter to the PWM wire without it connected to the fan, with laptop on:
here is what i found:

When GPU temps reached 105 degrees (C), the PWM input became a PWM output.
When I connected the wire back just by touching, the fan ran even faster than with the wire disconnected...

Now, without the wire connected, just-to-see, I saw the temp hit 105, then fall to 103 and sit there sometimes hitting 104 but stayed 103 most always....
sometimes back to 105... (degrees (C))...

I'll eventually add a diode in parallel with my switch to allow for the higher speed if it ever peeks there in game, but I had burnout running my GPU at 100% constant, so I probably dont need it...

Thoughts...?
post #4 of 5
Generally speaking, Laptops PC's run much hotter and lack the airflow of desktop PC's. Thus, the cooling profiles (PWM) would require a much steeper curve than normal. IMHO, If the laptop is not overheating, theres no reason to mess with cooling. If the modification you made improves the cooling and doesn't effect the operation of your laptop, then mission accomplished
post #5 of 5
Thread Starter 
The mod works great actually, constant max fan for gaming with option of quiet auto fan for in classes is great!

I'm thinking of doing this now in addition to the current project:

I have a thin fast 2.5 inch computer fan and runs fast, I was thinking of adding it to the inside under the laptop to pull air into the largest vent and blow it directly onto the GPU ram, cuz that still gets VERY hot for some reason...lol

My only problem is where to pick up the (+) 12 volts and (-) ground for the fan I want to add internally.
(I alredy checked and there is enough space for it.)

This fan is quiet, when i ran it on an external 12 volt DC source and attached everything it worked great

I'm just been having trouble trying to find where to pick up the 12 volts...

So asking your opinions?:
**Can I safley pick up the 12 v and ground from the existing fan supply??
(So the 2 fans are in parallel, only 12v and ground, not signal or PWM)
**Or will the extra current draw there kill the output at that source??

idk, I'm having trouble finding the pinnout on the mb, and looking at the components, they way the board is traced, I cant follow any lines to easily...
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