which fan connector do I use?

[mrwill]

It's been a while since I built a new system. I just got my case and it came with a few 230 mm fans that have a connector that has a pas-thru molex and a 3 pin connector. Do I use one or the other or do I need to use both (Molex and 3 pin)?

 

[Sysjack]

The pass through molex is just so you can daisy chain it with other fans/drives. The 3-pin is for if you want to power it through your motherboard. If you don't care about what speed it is running just go direct to the PSU. If you want to use motherboard fan speed control or monitor the RPM use the mobo adapter.

 

[Kenjiwing]

if its a single power connector it needs to be used... if its a passthrough it does not.

 

[mrwill]

Can I use both? I am thinking this will help power drain on my motherboard and I can control it if I need to.

 

[BillParrish]

It would not work that way, and it could cause problems. One or the other.

The fan would receive 12V from the molex and run full speed regardless of the 3 pin and if your motherboard controlled the aux fan connectors with voltage control the 12V from the molex would be fighting the reduced voltage from the motherboard header and I dont know what might happen. Nothing good.

Check your bios/manual and see if there are bios settings for the motherboard fan connectors. Most motherboards only control the cpu fan speed. But if yours did control fan speed it would help you decide between either the molex or the 3 pin.

 

[backwoods]

some of my 4 pin molex have a extra 3 pin so mobo can set fan speed