Asus X79-Deluxe Motherboard turns all fans to max when computer shuts down

[jonathanroper]

Hi!

I have a computer that uses an ASUS X79-Deluxe Motherboard. Every time I go to shut down this computer, the fans turn on to maximum speed as soon as the computer is off. The only way to then turn off the fans is to then go to the back of the computer and press the switch to stop the power.

Any suggestions regarding why this could be happening? One idea we have tried is to change the PSU but that didn't appear to help so we believe it has something to do with the motherboard or the BIOS.

Thanks!

 

[romirez]

Must be Nuvoton chip problem on your mobo.

 

[jonathanroper]

So would the only solution be to replace the mobo?

 

[romirez]

or fix the mobo

 

[larrycumming]

you can get a fan controller hub, but they usually require you to place a sensor on the cpu surface.

or you can get a fan splitter with molex input. it'll let your mobo pwm header control your fanspeed while the power is drawn from the molex input

both options let you separate your fan from your mobo's fan header, so they wont draw power from the mobo. when you turn off the computer, the psu molex should be cut off so your fans will not be powered

something is not right with your mobo, i'd get it fixed if I were you, in case there's further damage.

 

[jonathanroper]

Can I ask what the Nuvoton chip does? If I tried to replace it and it breaks, would it stop the computer working?

 

[larrycumming]

it's a microcontroller. it's not something you replace on your own and I would advise you not to if you don't even know what it does.

 

[romirez]

The NCT6791D is a member of Nuvoton’s Super I/O series capable of monitoring critical parameters in PC hardware including power supply voltages, fan speeds and temperatures. The NCT6791D supports both high accuracy current mode sensing and low cost thermistor mode sensing. The NCT6791D also supports the Nuvoton SMART FAN™ I and SMART FAN™ IV algorithms for fan speed control.

 

[jonathanroper]

Thanks for your answers. We tried adding a fan controller but unfortunately this didn't seem to work even when bypassing the motherboard completely. Are there any other possibilities that we could investigaste other than the motherboard and the PSU which we have already tried switching.

 

[larrycumming]

Thanks for your answers. We tried adding a fan controller but unfortunately this didn't seem to work even when bypassing the motherboard completely. Are there any other possibilities that we could investigaste other than the motherboard and the PSU which we have already tried switching.

this is very odd. how is your fan controller powered? by molex?

when your computer is off the power to your molex cable should be turned off too.

 

[Karadjgne]

Common issue with some older asus mobo's. Most normally, a bios update will fix the issue. Also include any/all mobo driver sets like USB family, audio, Lan, Intel management etc