Hi,
Just built my system and only thing I'm stuck on is the connecting of the Nexus 19.2 92 mm fan....
It has a 4-pin power connector and a 3-pin motherboard connector. Do I have to plug both in, or just use one option, and if so what is that best option?
On my previous build my stock HSF just had the motherboard CPU fan connection, so never seen this before.
Any help much appreciated,
Thanks, Danny.

You should only plug one or the other, not both.

I would use the 3-pin and plug that into the motherboard. Newer motherboards will measure the fan RPM and/or monitor your system temperature to increase or decrease your fan RPM accordingly.

Hmmm... wonder what the results of plugging both in would be. Seems like it might burn something out on the mb. This is something I'm not going to try to see what happens...

unless i'm mistaken, there wouldnt be any voltage differential across the lines, so the result would be rather unspectacular. more likely, nothing would happen

unless you're referring to a fan using PWM or something, in which case, i dont know what would happen.

Hi guys,
Thanks for the replies. My motherboard is an Intel PBZ 875.
Off the top of my head it has cpu fan, front and rear fan connections.
Guess I'll just stick with the motherboard cpu fan (3 pin) and leave the molex plug unconnected.
Danny.

I don't know of any PWM fans that have 4pin 'molex' connectors also so we'll just assume the usual Nexus-like 3/4pin configuration.


If a fan is connected to the mb sysfan (of which most? are speed controlled), then there could be a difference. The mb would be sending say 7v and the fan 4pin from the psu would be sending 12v on the same wire. If I knew more about electronics I'd probably know the outcome. I do know that a fan connected to the 3pin sysfan on an ASUS 690G worked for a couple of hours and then didn't (I might have been trying different fans without cycling power). The other two, CPU and PWR, worked fine. No other fan would work so had to rma it and the replacement has worked for a while now. Granted it might have been a cold solder joint.

Just got this description from a site selling this fan. I guess this is from the manufacturer:-

"The Nexus 92mm Real Silent case fan is equipped with a double sided 4-pin power connector and a 3-pin motherboard connector. This allows you to connect the case fan directly to the power supply or to the motherboard."

So I presume the 4 pin power connectors are for using the fan as a normal case fan or something.
But there are no instructions in the box.

It seems like the more recent P67 motherboards tend to use 4-pin rather than 3-pin fan headers. How would you connect a 3-pin fan such as the Nexus 92mm to a 4-pin motherboard fan header? Are there adapters?

Thanks

EDIT: I just realized that some P67 motherboards (in particular MSI's) have 3-pin fan headers in addition to the PWM 4-pin headers. Also, some of the ASUS 4-pin fan headers can be switched from PWM to voltage control mode.

I guess I can start a separate thread for this...