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Trying to understand the motherboards fan headers


pie

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First of all, thank you for taking the time to read my long post and thank you for trying to help me out. I appreciate your time and post and comments.

 

Gigabyte motherboard:

The motherboard has a 4-pin CPU fan header (CPU_FAN), a 3-pin fan header (SYS_FAN1), a 4-pin system fan header (SYS_FAN2) and a 3-pin power fan header (PWR_FAN). Each fan header supplies a +12V power voltage and possesses a foolproof insertion design. When connecting a fan cable, be sure to connect it in the correct orientation. Most fans are designed with color-coded power connector wires. A red power connector wire indicates a positive connection and requires a +12V voltage. The black connector wire is the ground wire. The motherboard supports CPU fan speed control, which requires the use of a CPU fan with fan speed control design. For optimum head dissipation, it is recommended that a system fan be installed inside the chassis.

So the motherboard can support 4 fans.

4-pin CPU fan (item #3)

3-pin sys_fan1 (item #4

4-pin sys_fan2 (item #5)

3-pin pwr_fan (item #6)

 

Can I control the fans using a program like SpeedFan or should I get a Fan Controller? I will have 1x5" bay and 1x3.5" bay (if I decide not to install the floppy drive) so I can install a fan controller in one of these 2 slots.

 

What is the difference betwen the 3-pin and 4-pin fan connectors? In the motherboard they look almost the same, except the 4-pin has 1 extra pin.

 

Antec solo case:

The case includes one 120mm TriCool fan installed in the rear. This fan has a three-speed switch that lets you choose between quiet, performance, or maximum cooling. The fan is installed so that the air is blowing out of the case. Connect a large 4-pin connector from the PSU to the male 4-pin connector on the fan.

Speed: High 2000 RPM

Input current: 0.24A (MAX)

Air Flow: 2.24 m^3/min (79CFM)

Statif Pressure: 2.54 mm-H2O (0.10 inch-H2O)

Acoustical Noise: 30 dBA

Input Power: 2.9W

 

Speed: Medium 1600 RPM

Input current: 0.2A

Air Flow: 1.59 m^3/min (56CFM)

Statif Pressure: 1.53 mm-H2O (0.06 inch-H2O)

Acoustical Noise: 28 dBA

Input Power: 2.4W

 

Speed: Low 1200 RPM

Input current: 0.13A

Air Flow: 1.1 m^3/min (39CFM)

Statif Pressure: 0.92 mm-H2O (0.04 inch-H2O)

Acoustical Noise: 25 dBA

Input Power: 1.6W

 

You can install two 92mm fans into the fan cage in front of the internal 3.5" drives. These fans must be installed so that air is blowing into the case. We recommend using Antec 92mm TriCool fans to balance quiet performance with maximum cooling.

The case fan has 2 wires that go into a 4-pin. This isn't the same 4-pin's from the motherboard. You know in the back of your IDE HD/CD drive, you have the 4-pin power connector? It looks like that. From some other threads I read, I thought you couldn't control fans with these kind of connectors?

 

Item #5 (4-pin sys_fan2) and #6 (3-pin pwr_fan) are closer to the front of the case (front/right side of the motherboard). The case has room for 2x92mm fans.

 

Item #4 (3-pin sys_fan1) is at closer to the back of the case (back/left side of the motherboard). Only thing I can think about putting there would be the 120mm back case fan. But the pins are different. Is there any kind of converter to use?

 

I need 3 fans, one for item #3 (4-pin CPU fan), and if possible, for item #5 and 6 (that will go into the front of the case). Even if I can't plug those two fans into item #5 and #6 in my motherboard, I'd still like two fans for the front of my case.

 

I'll let the motherboard handle the CPU fan, is that a good idea? I want to control the fan at the back of my case, and the two at the front of my case (use them around full speed when I work, but have the option of turning them down low when I go to bed and let the computer just go idle while it downloads random things)

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First off it's generally not a good idea to run fans larger than 80mm off the motherboard except maybe low power 92mm fans. Now that's not to say you WILL have problems, but it adds alot of stress during startup to get a 120mm spinning and as it turns out may motherboard fan headers arent up to the task. (They can burn up and either take one or possibly ALL your fan headers out)

 

When it comes to fans with 4 pin molex (the now "old" Hard Drive connection) chances are they should NOT be plugged into the board even with adapters to match the pins, the reason being the liekly higher power draw that could damage the board.

 

Now as for using 3 pin fans with 4 pin connectors, you can. They'll work just fine, the 4 pin design is for PWM fans like the newer Intel stock cooler fans. Speedfan MAY be able to adjust fan speeds, though in my experence it's been around a 50/50 shot of having it actually work with various boards. Over all though if you really want to be able to adjust the fan speeds the BEST option is to buy a HARDWARE fan controller and use that. And any fan you're running full speed all the time is best left running straign off the power supply (likely using a 4pin molex to 3 pin adapter)

 

Now all of that advice is staying more on the side of caution, so you can possibly get by using a few different options, but that's what I would do. Ok maybe that's a lie, I actually have one low power 120mm fan running off a motherobard fan header atm, but the system almost never restarts (getting the fan moving is when it needs the most power afterall) and for the time being I'm willing to take the risk. In otherwords, to play it safe do as I say, not as I do :lol:

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4pin vs. 3pin

4pin molex connectors have a yellow, a red, and two black wires. The black wires are both ground. The red is 5v, and the yellow is 12v.

 

3pin fan connectors usually have a red, yellow, and black. The black is still ground. The red is 12v, and the yellow is a fan speed sensor.

 

So the difference is the speed sensor. Also, you will notice that most fans with a connector for 4pin molex actually only use two of those wires (one ground, and one 12v), so even though it's 4 pins, you're really only using two. The third wire on the 3pin connector is what allows your motherboard to tell you the speed your fans are spinning at.

 

 

Fans On Motherboard vs. Fan Controller

Most people try not to plug any fans into their motherboard because they worry about the small traces (wires) on the board not being able to handle the power draw. On low RPM fans with low power draws, it's not actually a big deal, but I still prefer to run all my fans off of fan controllers instead. Fan controllers aren't that expensive and I find the functionality much nicer than adjusting things through software. But if you're going to run fans off the mother board, just be sure to keep it to low draw fans.

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Thank you both for the quick response. Actually learned A LOT about fans from those two posts alone.

 

For the Heatsink XP-90: I was originally planning on using a 92mm fan and plugging it into the motherboard. Sometimes I leave my computer running for days, and other times I might turn it off at night and turn it back on again the next day. But after reading the post, I'm now thinking about sticking with my old VANTEC SF8025L 80mm Case Fan for the CPU.

 

That leaves 2x92mm case fans, and 1 fan controller (which will control 3 fans or 4 depending on what you guys think about the heatsink/fan). The Sunbeam seems popular, and I'm leaning toward that. The lights seem like a double edge blade. I like the fact that it changes color when you change from Medium to High, but don't like the fact that the lights are BRIGHT. I'm also thinking about the Hardcano 13, but there are a lot of bad reviews about the Hardcano 12 which is putting me off from the Hardcano 13.

 

What's everyones favorite fan controller? I guess I'll base my 2x92mm fans on the fan controller I get.

Edited by pie

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As long as it's a low power 92mm and not somthing too powerful i think you'll be just fine plugging it in, but you could always plug it into a fan controller and just use it to control temps (though you may need to hook the RPM sensor wire to the motherobard so it doesnt think the CPU fan has failed, many boards wont even POST if they think there's not a functional CPU fan. (some have a bios option to diable this feature, but if your overclocking/need to reset to defaults you may spend alot of time remembering that you previously diabled that and cant figure out why it wont POST...Not that I've ever done that...really :D)

 

Anyway glad to have helped a little.

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though some mobos are crazy and won't function correctly if the cpu fan is not connected so I use a fan controller for most fans and just plug a small one into my cpu fan header as I am using water cooling and do not have a cpu fan it is usually my ramfan. ;)

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i plug my rads fans into my cpu and pwm fan headers on my mobo.

 

Both work fine.

 

I control these via software i created in VB and they raise in rpm to how much load i place on the cpu (my program reads PCwizard 2008)

 

sometimes they fail to spin up but if i touch them they start spinning

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First off it's generally not a good idea to run fans larger than 80mm off the motherboard except maybe low power 92mm fans. Now that's not to say you WILL have problems, but it adds alot of stress during startup to get a 120mm spinning and as it turns out may motherboard fan headers arent up to the task. (They can burn up and either take one or possibly ALL your fan headers out)
Most, if not all, 120mm fans spin at significantly less RPMs than 80mm fans, so why would those be more stressful?

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