Tom's Hardware > Forum > Overclocking > Heatsinks & Air Cooling > [Solved] Chassis Fan speeds always maxed, 4 pin header coming out of PSU???

[Solved] Chassis Fan speeds always maxed, 4 pin header coming out of PSU???

Forum Overclocking : Heatsinks & Air Cooling [Solved] Chassis Fan speeds always maxed, 4 pin header coming out of PSU???

SO I haven't been able to find any information on this, hope you guys could help. I just put together my new build and I've everything working just fine, well almost. The 3 case fans that came with my case, are all powered correctly but they uncontrollable! They run at full speed non stop, which is quite loud. This is my PSU: http://www.newegg.com/Product/Prod [...] max%20700W

How they are connected:
-Each fan is connected directly to the power supply's 4 pin molex connectors. The fan themselves only have 2 of the pins being used.
-Nothing about the fans is connected to the motherboard
-The fans themselves don't have any header connectors to connect right to the motherboard, just the 2 pin molex connectors for power
-However, on the cluster of 3 molex connectors powering the fans there is a 4 pin header coming out of the PSU and I have no idea where to plug it in. I tried CHASSIS_FAN1 4-pin connector on the motherboard but the thing wouldn't even power on.

I tried changing the fan speeds in the BIOS, nothing changed... The fan RPMs dont even show up in the BIOS it's just N/A, only the CPU fan speed shows up cause thats connected right to the MOBO.

SO, does any one have any ideas how I can make the chassis fans more controllable? THANKS!

Reply to emlarsen2

What fans and case?
The psu has pretty much nothing to do with the fans other then providing power.
2pin fans are not controllable you need 3 or 4 pin fans for mobo support.
Older psu's have a 4pin fan cable = goes into Power_ fan header on mobo.(psu fan control)

Reply to davcon

What Motherboard, what case?

Reply to DelroyMonjo

mobo: http://www.newegg.com/Product/Prod [...] %204%20970

case: http://www.newegg.com/Product/Prod [...] 6811119196

The only cords going from the psu to the fans are the molex power connectors. The psu has this little 4 pin cord that looks like it plugs into the motherboard. It's on the same cluster of cables as the 3 molex power connectors coming out of the psu (that are used to power the 3 fans). The molex power connectors coming from the fans that need power from the PSU only have 2 of the 4 pins that are usually there (thats not really anything that matters.) The fans themselves have no little header cables that can go to the mobo. Thats why im wondering about the 4 pin connector coming out of the PSU, could that be a controller for the fans?

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Reply to emlarsen2

No. That goes to a temperature sensor on the motherboard to automatically control the PSU fan. Modern PSU's (yours isn't) control their own fan and do not need this connection.

"The molex power connectors coming from the fans that need power from the PSU only have 2 of the 4 pins that are usually there (thats not really anything that matters.) "
It may. The two wires on the fans connect to the yellow and black wires (12 volts), so the fans will run at full speed. You can either get a fan controller or try the 7 volt modification:
http://www.techpowerup.com/articles/other/137

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Reply to jsc

jsc wrote :

No. That goes to a temperature sensor on the motherboard to automatically control the PSU fan. Modern PSU's (yours isn't) control their own fan and do not need this connection.

I've tried plugging that in and results in the PC not even powering on. Push the power button and nothing happens. Unless im plugging it in the wrong place, where does that 4 pin connector go?

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Reply to emlarsen2

emlarsen2 wrote :

I've tried plugging that in and results in the PC not even powering on. Push the power button and nothing happens. Unless im plugging it in the wrong place, where does that 4 pin connector go?

If that 4pin lead were to go anywhere it connects to pwr_fan.
Otherwise if your psu fan works fine without it plugged in i wouldn't worry about it.
All the case fans should be fine using the psu molex for power = i have 2 CM cases and power all my stock case fans this way.
Your mobo has alot of fan headers = bonus!
Your case however has a very limited amount of fan options = pretty much what's included stock.

Reply to davcon

The case can add 2 more on the side, but it comes with 3 which is quite a bit.

The PSU fan works just fine, but that still doesn't answer the question about the other fans being on full speed all the time. If I plug this 4 pin header in, will that control the case fans as well as the PSU fan?

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Reply to emlarsen2

emlarsen2 wrote :

The psu 4 pin fan lead has nothing to do with your other fans.

Reply to davcon

Best answer

emlarsen2 wrote :

mobo: http://www.newegg.com/Product/Prod [...] %204%20970

case: http://www.newegg.com/Product/Prod [...] 6811119196

The only cords going from the psu to the fans are the molex power connectors. The psu has this little 4 pin cord that looks like it plugs into the motherboard. It's on the same cluster of cables as the 3 molex power connectors coming out of the psu (that are used to power the 3 fans). The molex power connectors coming from the fans that need power from the PSU only have 2 of the 4 pins that are usually there (thats not really anything that matters.) The fans themselves have no little header cables that can go to the mobo. Thats why im wondering about the 4 pin connector coming out of the PSU, could that be a controller for the fans?

:ouch: For crying out loud, don't connect floppy disc power to your motherboard.
http://www.raidmax.com/psu/rx_700ac.html

You do have a modern powersupply, it has no fan connection that goes to the motherboard.