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Case fan stupid questions..

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December 7, 2012 12:33:18 AM

Alright i bought an apevia 80 mm and 120 mm fan. The 120 fan has a mobo 3 pin connector and molex male and female connectors. The 80mm only has molex male and female. My mobo is an msi fm2 hudson d3 a 75 chipset. Dont know the exact model.. Now i wana connect both to the mobo. Can i connect the 120 to mobo and the 80 to one of the molex from the 120?
a b B Homebuilt system
December 7, 2012 1:11:48 AM

While I can't say for sure, I don't think it would be a good idea. I would guess that a motherboard's SYS_FAN connection is only intended to power a single fan. Check your motherboard specs as you may have more than one chassis fan power port. If not, then I'd run a molex, direct from the power supply to FAN1, and then connect FAN2 to FAN1.

-Wolf sends
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a b B Homebuilt system
December 7, 2012 1:27:55 AM

PCNOOB562 said:
Alright i bought an apevia 80 mm and 120 mm fan. The 120 fan has a mobo 3 pin connector and molex male and female connectors. The 80mm only has molex male and female. My mobo is an msi fm2 hudson d3 a 75 chipset. Dont know the exact model.. Now i wana connect both to the mobo. Can i connect the 120 to mobo and the 80 to one of the molex from the 120?



Basically, what you need to do is connect the 120 mm fan (with the 3 pin Mobo header) to the mobo 3pin fans connector. You can use any fan connector as long as it's NOT the one intended for the CPU_FAN. For the 80 mm fan you will have to connect it to one of the PSU molex connectors. If you really feel the need to connect it to the mobo you can cut off the molex connector and add a mobo compatible connector from another fan.

If you want to connect both fans to one Mobo connector, that's OK as long as your motherboard can supply sufficient current to run both fans at the same time. You can look up the output current for your fan connectors in your motherboard manual. The fans should have the current rating specified on the label or on the package. The total current required for all fans is the sum of the current ratings for each fan.

Edit: corrected typos
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a b B Homebuilt system
December 7, 2012 2:19:48 AM

I'm guessing that will be OK, because most mobo SYS_FAN ports can support up to two fans in parallel. Unfortunately, specs won't tell you what you need to know. Even if the mobo manual tells you the current max for one of the fan ports, comparing that to the sum of currents for the two fans will not answer the question. That's because the real limit is the brief heavy STARTING current of the two fans. But as I said, most people find you can run 2 fans off one port, not more.
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December 7, 2012 2:34:34 AM

Yes so if i connect the 120 to mobo i can connect 80 to 120 from molex connection. But will it work only when its hot that way or just run continous.
Also one more thing i made the holes to screw on the 120 fan at bottom of case. Do i need to make vent holes at the bottom for it to suck outside air or will it work with out the vent holes
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a b B Homebuilt system
December 7, 2012 3:09:51 AM

Yes, connect that way. Your mobo normally will control the fan speed according to the internal case temperature. (You can adjust the details of this if necessary -read you mobo manual - but don't worry about that for now. It does this by varying the voltage supplied to the 3-pin 120 mm fan. Since you will have two fans in parallel fed by that voltage, they both will change speed according to the mobo's actions. However, when the BIOS tells you the speed of that case fan, that will be ONLY the speed of the 120. There is no speed signal being generated by the 80 mm fan and sent back to measure.

If you have mounted a fan against a solid sheet of metal, it will do almost nothing! You must mount each fan mated up to a grille or opening in the case so that it can move as much air as possible from outside the case to inside (intake), or from inside to outside (exhaust). Intake fans ALWAYS should have a dust filter on their intake side. Do not place filters over an exhaust fan.
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