where do I connect the case fans?

[cheese321]

I have a gigabyte p35 mobo and a thermaltake 500w psu. I was wondering where do I connect my case fans to? I thought I am suppose to connect the fans to the 4-pin peripheral connectors from my psu but I noticed my mobo has "sys fan" and "power fan" slots. Also if I am suppose to connect the case fans to the mobo, does it matter which slot I use for the 120mm fans and the 80mm fans? Thanks

[rave]

im pretty sure you should connect them to your the 4 tiny pins on your mobo. this will enable the motherboard to regulate fan speed and what not. im not sure what a powerfan is though.

[shadowpr]

i have my fans connected directly to the psu. they seem to work perfect to me.

[juppy]

Me personally, I hook case fans to the 4-pin molex connectors on the power supply. Mainly for one reason: header burnout. Some fans pull more current than others, and if the fan pulls more current than your little motherboard header ("sys fan", etc) is rated for, it can burn that header out and render it inoperable.

The only real advantage to plugging one into the motherboard anyway is the speed monitoring capability. If you hook directly to the psu, you don't have any way to monitor fan speeds. Some people make a special plug and splice it to their fan so they can plug the power wires into the psu connector and plug the monitoring wires to the motherboard. That's only advisable if you know what you're doing though, so you don't end up wiring something wrong and frying a component.

[cheese321]

Originally Posted by juppy Me personally, I hook case fans to the 4-pin molex connectors on the power supply. Mainly for one reason: header burnout. Some fans pull more current than others, and if the fan pulls more current than your little motherboard header ("sys fan", etc) is rated for, it can burn that header out and render it inoperable. The only real advantage to plugging one into the motherboard anyway is the speed monitoring capability. If you hook directly to the psu, you don't have any way to monitor fan speeds. Some people make a special plug and splice it to their fan so they can plug the power wires into the psu connector and plug the monitoring wires to the motherboard. That's only advisable if you know what you're doing though, so you don't end up wiring something wrong and frying a component.

I am wondering which place is the standard way of connecting the case fans. If I connect the case fans to the 4-pin molex connectors on my PSU, does it mean that the case fans would always be running and never stopping since the mobo isn't controlling it?

[maxnik]

another option is to buy a fan controller. Some of them go into 5.25 bays and can control multiple fans.
Also if you can try to find info on how much current your fans draw and make sure it's less than what motherboard headers are rated for.

[XenaWP]

I like using the mobo connection so that the fan speed is variable. Fixed speed seems louder to me, and I like a reasonably quiet system.

Also hearing the speed ramp up gives me a clue that something is going on with temps.

If simply connecting a fan to a mobo header makes the header "burn up," that mobo manufacturer is going to be hearing a LOT from me.

[Cricket]

Originally Posted by XenaWP If simply connecting a fan to a mobo header makes the header "burn up," that mobo manufacturer is going to be hearing a LOT from me.

This is something that happened a lot back in the later 90's when folks were using very high RPM 60mm fans (like the infamous Delta Black Label and Vantec Tornado fans) on their heatsinks when overclocking...those fans drew more juice than the header could handle and the header would fry. Most times there would be no other damage and the user would just have to connect the fan directly to the power supply.

With today's motherboards I don't hear about this problem much but I think it's because the heatsink makers went to bigger, slower spinning fans to don't require as many amps to work and this may be what is keeping the fan headers from burning out. The fan headers are probably designed to handle more power output too.

In my own computers I only have the CPU heatsink fan connected to the CPU FAN header on the motherboard, I connect the case fan (I only use one exhaust fan) directly to the power supply out of habit.

Cricket

[Dswissmiss]

Not to detract, but does this still happen with the HSF connected to the mobo?
I think this may have happened to my old ASUS P4S533. After OC'ing the fan stopped spinning so I had to get a splitter and connect it to my PSU as well.

[LeftyAce]

I've had no issues with an aftermarket fan on my A8N32. It's connected only to the motherboard CPU fan header. The fan is a large diameter, and fairly quiet (low RPMs) so it's probably low current as Cricket pointed out.

[Cricket]

Originally Posted by Dswissmiss Not to detract, but does this still happen with the HSF connected to the mobo? I think this may have happened to my old ASUS P4S533. After OC'ing the fan stopped spinning so I had to get a splitter and connect it to my PSU as well.

I think the motherboard manufacturer's did beef up the fan headers to handle more current draw put on them by higher RPM fans but I don't think the PCB circuit traces were meant to handle really high amp draws. But with the larger fans used by today's 3rd party CPU heatsinks I don't think it's as much of a problem as it used to be.

But this is why I just stick to the stock heatsinks and fans...no worries as far as the fan headers go.

Cricket

[juppy]

Originally Posted by cheese321 I am wondering which place is the standard way of connecting the case fans. If I connect the case fans to the 4-pin molex connectors on my PSU, does it mean that the case fans would always be running and never stopping since the mobo isn't controlling it?

Yeah, that's how it would be. There's no speed control when they're hooked directly to the power supply.....just on at full speed when you turn the computer on, and off when you shut down. Unless you do like maxnik suggested and use a fan controller. In that case you would hook the fans through the controller and could control the speeds that way.

I agree with Cricket about the reasoning for the headers burning out. If you stick to regular stock heatsink fans, you're probably not going to have much of a problem. The system I'm on right now has the heatsink fan hooked to the CPU_FAN header, and it's NOT a stock fan....*BUT*, I researched what that header could handle and the fan I hooked to it was well enough under the maximum current that it wouldn't cause a problem. My other case fans (one front, one back) are both hooked to the power supply though.