Possible to install 2 fans on single motherboard header?

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ebduncan

[H]ard|Gawd
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Feb 1, 2008
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Well first things first.

The motherboard is a Gigabyte 990FXA UD3 rev 1.0
The Fans are Corsair SP120's

According to gigabyte the fan headers can support up to 4 amps. Corsair's website say they draw 1.8a each at full load. There is little room for error here, so figured i'd ask.

The reason, currently the fans are being run @ 7 volts (supplied voltage reducers). They are quiet, yet when gaming for long sessions the computer can heat up, and I'd like to run the fans at a higher voltage during these times. I figured I could just hook them up to the PWM on the motherboard and have the motherboard control the voltage when things heat up.

Its not dire the computer doesn't overheat or crash or anything, just would be nice to lower the temp a bit when its running at full load. I rather not burn out the fan header.
 
As close as the combined amperage is to the mobo specs, I personally wouldn't. Just my two cents, but the potential downsides seem to outweigh the benefits.

A silly question for you: what about the other fan header? That motherboard has two. Are they both pwm? Can you just hook one fan up to each one?
 
Tuthmose said:
As close as the combined amperage is to the mobo specs, I personally wouldn't. Just my two cents, but the potential downsides seem to outweigh the benefits.

A silly question for you: what about the other fan header? That motherboard has two. Are they both pwm? Can you just hook one fan up to each one?
Click to expand...

Yes the motherboard has 2 pwm fans. Cpu fan and system fan. Pretty sure the system fan pwm only increases when the system temp is high, and the cpu pwm fan increases when the cpu is hot. Though they could be linked to a single temperature target. I am using the system fan PWM header for a 120mm side panel fan.

I think I am just going to hook it up. I had a Antec 920 before and it ran two fans and a pump from the cpu fan header and USB. Not sure what the USB powered, probably just the RGB LED and pump.

The fans would never get to max speed anyways and draw max current. The Akasa Pwm splitter would work as well. Might order one of those and just run it off the motherboard for now.


Here is a picture of the system, the fans in question are currently mounted on the top radiator.
 
ebduncan said:
Pretty sure the system fan pwm only increases when the system temp is high, and the cpu pwm fan increases when the cpu is hot.
Click to expand...

Yeah, makes sense - I'm not at all sure what the pwm targets would be on each.

Now that I see the system (nice rig!), it occurs to me that you could just split the difference and hook one of those rad fans up the pwm header, and leave the other as is. Just spooling up one of the fans might drop the temps sufficiently to where you want them, and it would keep the sound at a lower level. Perhaps you don't necessarily need to increase the fan speed on both to get your desired results? It would be a fast-n-free experiment, in any case.
 
works fine for now.

Both fans are hooked up the PWM cpu fan header now.
 
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