Case Hookup Question

[Baldrick]

I've just got my new case (Cooler Master CM-690) and I've got a question.

The case has 3 120mm fans, all with three pin connectors. The motherboard (Gigabyte P35-DS3P) has 2 System Fan headers and 1 Power Fan header. What's the difference? Should I use all three of these headers for my 3 case fans? Or should I hook up some or all directly to the PS?

Why would one of the headers be 4 pin? It really doesn't matter which fan I hook up to which header does it?

Now, if only Dell would ship me my 8800GT....

Thanks.

 

[dmroeder]

Maybe I'm misunderstanding this, but you have some fans with the connectors that plug into the motherboard (with 3 pins) and you have some fans with standard molex connectors (from you power supply) correct?

The 3 pin ones most likely have a speed sensor, so that your motherboard can control them. The molex ones just run at full speed all the time. How you hook them up is up to you, it doesn't really matter which one you use.

 

[aadamszc]

With my limited knowledge of computers, I concur with dmroeder. You will probably want to hook up to the side fan to the molex connector. That way, the side fan would always be blowing cold air on your components.

this would also help in airflow...because you wouldn't want the front fan blowing 100% all the time, and the back one not pulling it's weight.

 

[Baldrick]

Sorry for not being clearer.

All 3 of my case fans have a 3-pin molex. The motherboard has two 3 pin molex and one 4-pin molex.

One of the two system fan headers on the MB is a 4-pin the other is 3-pin. Also, the power fan header on the MB is 3-pin.

I'm just wondering what the differences are between these three headers on the MB and can I hook my case fans to any of them or do they have specific purposes.

Also, is it recommended that I hook any of my case fans directly to the PS, bypassing the MB and it's fan speed control.

Thanks.