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adamtech78

join:2006-01-25
Chicago, IL

[Modding] quiet PC: 2pin fan into variable speed?

Hello.
I have a tower with a i7 2.8 that is cooled by a closed circuit radiator from corsair, H50 I believe.

That fan is mounted on the back of the case blowing air in through the radiator and I have a 14mm case fan blowing air out.
Lately that fan was noisy (bearing) and I replaced it with a Thermaltake Turbofan A2491. While I don't have the buzzing sound I'm not a "fan" of the noise.

While the mobo is overclock friendly I don't plan on overclocking the CPU but I would like to have things quiet.

Is it possible to purchase something that will connect the 4pin molex connector into a temp probe of some sort and with that slow down or speed up the fan?

The mobo only has one hookup for a 3pin case fan and that's down low on the intake where the hard drive sits.

I have created a big L out of cardboard shielding the CPU from the rest of the system (the PSU sits on the bottom).

Then fan I have now is rated at 16dba.

matt5

join:2001-10-06
Lagrangeville, NY
Lost, what is using the CPU fan header?

adamtech78

join:2006-01-25
Chicago, IL
The fan that is at the back of the case pulling air in and through the radiator is using the CPU fan header.


a_large_rock

join:2003-08-02
Waterloo, ON
Reviews:
·Start Communicat..
Yes there are temperature dependent fan controllers for 4pin molex that just plug into the molex.. they run about $15 and i haven't had any luck with them. Some case fan control panels also do temperature control.. your looking at ~$45 for those.

So you have two fans?
One fan hooked up to the 4pin CPU header.
One fan that uses a 4pin molex hooked to the PSU.
And no fan hooked up to the 3pin case fan header?
Wouldn't a 4pin molex to 3pin header adapter work assuming you have some form of automatic fan control turned on in the BIOS?

matt5

join:2001-10-06
Lagrangeville, NY
reply to adamtech78
Just get a splitter? I have 3 fans connected to my cpu header... it does have an auxiliary molex for power as I do not want to blow the fan header with 3 fans pulling juice but you should be fine with 2 not super high draw fans on one header.

adamtech78

join:2006-01-25
Chicago, IL
reply to a_large_rock
Click for full size
Attached is a drawing.

the fan "B" is the one I replaced yesterday.
sitting at idle the GPU temperature is at 38*C with fan C disconnected, when the fan is connected the GPU temperature at idle shows 41*C.

Fan B is marked at 16dba on the box.

matt5

join:2001-10-06
Lagrangeville, NY
So again, unless I am lost, you want the fan to run slower, unless the cpu gets hotter or so? So again, 4pin splitter... and you can plug both into the cpu fan header and have them controller based off CPU temp (that you can set custom speeds in the bios for based off CPU temp) or do you not want that?


Thedude99

@comcastbusiness.net
Did not know I can use such splitter. Does newegg carry this?


a_large_rock

join:2003-08-02
Waterloo, ON
Reviews:
·Start Communicat..

4 edits
reply to matt5
said by matt5:

Just get a splitter? I have 3 fans connected to my cpu header... it does have an auxiliary molex for power as I do not want to blow the fan header with 3 fans pulling juice but you should be fine with 2 not super high draw fans on one header.

You are talking about a product like this:
»www.newegg.com/Product/Product.a···12119248

The Ground and a steady +12v supply comes from the 4 pin Molex connected to the PSU; The speed of each fan is controlled by a pulse width modulated signal from 4th pin of the fan header and connected to circuitry within the fan that varies the fan's duty cycle.

Adapters like these don't work on fans with 3 or 2 pins (not PWM) because the speed of these fans is controlled by varying the supply voltage. If you drive a 2 or 3 pin fan from these you will just be driving them at full speed (12V)

You might be able to use a normal splitter, but that would mean both fans are being powered by one fan header; which depending on your fans, and the power rating of that header, might blow the header on the motherbaord. You would also need something to convert the molex to 3 pin :/
»www.newegg.com/Product/Product.a···12200455

matt5

join:2001-10-06
Lagrangeville, NY
Losing me here again... the Thermaltake Turbofan A2491 is a 4pin, as far as I can see? Site I guess could have been wrong...

You can normally run 2 normal fans from one header no issue... start running ultra krazes... different story...

So a 4 pin splitter would solve the issue...

That or I need some sense slapped into me.