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4 Pin fans run at 100% speed at my 3 pin sockets mobo.Too much noise

Last response: in Motherboards
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October 14, 2012 2:23:18 PM

Hi.I recently bought some aftermarket fans for my pc. Cause my M3A78T runs hot at 52-53 under load.
My specs are Phenom II X4 940,M3A78T,8 GB RAM,GTS 250, Chieftec 650W, WD 500AAKS SATA and the case is a silverstone precision PS02.
So i bought these fans COOLERMASTER R4-BMBS-20PK-R0 BLADE MASTER FAN 120MM 2 of them.
These fans have a 4 pin connector.The three connectors of my M3A78T are all 3 pin(cha_fan1,cha_fan2 and PWR Fan.)
When i install my new coolermaster fans to any of these 3 pin sockets,the fans work at 100%.They offer a considerable good airflow for a 120mm fan(76,8CFM) and lower my mobo temp at 43 under load.However the noise in unbearable.
I tried to use speedfan but althought i have a pc since 1995 i cannot make it work correctly.(specifically i cannot link the pwm indicators at speeds tab to the apropriate fan installed at my pc)
I tried to use 3 to 4 pin adaptors but it didn't worked.The fans remain idle or made sporadic movemets and then stopped.

Can anyone help?any idea??

Thanks in advance and sorry for my poor english.
a b V Motherboard
October 14, 2012 3:58:03 PM

The only way those fan can be controlled is with a four pin connector on the motherboard, they are called pulse width modulation fans (PWM) and are controlled by temperature sensors on the motherboard.
October 14, 2012 6:22:32 PM

^^^
Thanks Knightdog. At least i will not spare any more time with this now that i know that all efforts are in vain.Damn. 24 euros for nothing :) .Anyway i will know this for the future.
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a b V Motherboard
October 15, 2012 1:22:20 AM

Save fans for a future build or sell them to a friend.
October 15, 2012 1:37:54 AM

Maybe im wrong, but i think you can control the rpm of the fans if your mobo has the option through the BIOS settings. My MoBo has this setting and it controls the fan with the voltage that arrives to the fan. It "ask" you in the Bios when you put the "Smart Fan" Enabled, if u want to control the rpm of the fan via PWM or with Voltage.
October 15, 2012 8:55:28 AM

xJATOx the BIOS in M3A78T does not offer this option.The only relevant that has is the option is to activate the Qfan.If you enable this then in the submenu gives you three choises."Silence" ,"optimal" and "performance" mode.No option to control the fans in any other way.I am kinda dissapointed.Also to add that the in the optimal setting the fans run at 50% aproximately even if the asus probe shows the MB temp to reach 51-53 :)  .That sucks.So i connected my most silenced fun an enermax apollish 12omm to a molex in order to work at 100%.And the 140mm roof fan to the cha_fan1 port in order to work to 50%.(cause in 100% makes tremendous noise".
Bottom line :enermax 120mm apolish is the only fan i am satisfied with it is really silent and efficient.I recommend it to anyone :) 
!