My motherboard, an Asus A8N SLI, has a single 3 pin connector near the rear of the board. My case has two 80mm fans in the rear. I have seen a 3 pin Y cable at several on line retailers. Can the mobo supply enough juice at that one connector to run two fans?
Two fans on a single motherboard connector?
- Thread starter Mudbone
- Start date
Possibly, but I wouldn't risk it. You'd need to have really low powered fans to avoid exceeding the mobos amp rating. Much safer to use a 4 pin molex adapter.
Check the Manual for Max amps as I have seen them claim up to and over 1.0...those X2 would = .3...keep in mind that there is no advantage by doing this method.
Just buy a three to four pin wire adapter and plug them into the PSU if you have any free rails.
3 to 4 pin converter
Or you can just buy one of these:
3 pin splitter
3 to 4 pin converter
Or you can just buy one of these:
3 pin splitter
BonzaiDuck
Lifer
- Jun 30, 2004
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I declare myself totally exempt of responsibility for adverse consequences due to this post.
I've been poking around and investigating the limitations of mobo fan-headers. So far, the best advice I've obtained is as follows:
1) The mobo fan-headers are all connected to a single voltage regulator on the motherboard.
2) Manufacturers have become wiser in the last two generations of motherboard fan accommodations, providing enough voltage for a range of fans.
For example, my ASUS P4P800 has three fan-headers labeled "CPU_FAN", "PWR_FAN", and "CHA[ssis]_FAN". The mobo manual ambiguously states that the headers are designed to accommodate fans with amperage draw between 340 and 740 milli-amps, or a cumulative draw of 2.22 Amps. It was never clear that there was an individual fan-header limitation (e.g., 0.74 Amp) in the event you chose to use only a single header to power a fan exceeding the individual fan guideline without drawing power from the remaining headers, but (1) seems to clear up the confusion.
That being said, I currently have a single 0.80 Amp fan connected to "CPU_FAN", and a 0.48 Amp fan connected to "PWR_FAN", choosing to use the third header strictly for monitoring a string of fans connected to a front-panel rheobus. You should only connect the monitoring wire from any single fan to such a fan-header, nevertheless.
You might be able to string more than one fan connected in parallel to a mobo fan-header, but I don't recommend it. I would recommend it "more" if they are dual or identical fans, connected in parallel, with a combined amperage draw that does not exceed the motherboard spec. I recommend it "less" if they are fans drawing different amounts of current, even within the mobo spec. I am reasonably certain that you should only connect the monitoring wire from one of those fans, but I submit myself readily to further guidance and "correction" by others.
I've been poking around and investigating the limitations of mobo fan-headers. So far, the best advice I've obtained is as follows:
1) The mobo fan-headers are all connected to a single voltage regulator on the motherboard.
2) Manufacturers have become wiser in the last two generations of motherboard fan accommodations, providing enough voltage for a range of fans.
For example, my ASUS P4P800 has three fan-headers labeled "CPU_FAN", "PWR_FAN", and "CHA[ssis]_FAN". The mobo manual ambiguously states that the headers are designed to accommodate fans with amperage draw between 340 and 740 milli-amps, or a cumulative draw of 2.22 Amps. It was never clear that there was an individual fan-header limitation (e.g., 0.74 Amp) in the event you chose to use only a single header to power a fan exceeding the individual fan guideline without drawing power from the remaining headers, but (1) seems to clear up the confusion.
That being said, I currently have a single 0.80 Amp fan connected to "CPU_FAN", and a 0.48 Amp fan connected to "PWR_FAN", choosing to use the third header strictly for monitoring a string of fans connected to a front-panel rheobus. You should only connect the monitoring wire from any single fan to such a fan-header, nevertheless.
You might be able to string more than one fan connected in parallel to a mobo fan-header, but I don't recommend it. I would recommend it "more" if they are dual or identical fans, connected in parallel, with a combined amperage draw that does not exceed the motherboard spec. I recommend it "less" if they are fans drawing different amounts of current, even within the mobo spec. I am reasonably certain that you should only connect the monitoring wire from one of those fans, but I submit myself readily to further guidance and "correction" by others.
I do it, though I am not sure if it was safe to. I have a Gigabyte Nforce2 mobo and have 2 Panaflo 80mm fans connected to one 3-pin outlet, and they work fine.
BonzaiDuck
Lifer
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Well, if they are identical and since the Panaflo 80's are probably in the 0.17 to 0.50 Amp range, you shouldn't have a problem.
My own difficulty derives from the fact that (at the very least) ASUS is not implementing the fan-control features of anything but the CPU fan, despite the full potential of the WinBond super-IO controller. I want to balance and automatically vary the speeds of both my CPU fan and my exhaust fan(s), because they are connected with a ducting solution. That leaves me with the option of either connecting dissimilar fans to the CPU header when my currently-chosen CPU fan draws 0.80 Amp to begin with, or finding another software-driven, USB-connected automatic/programmable fan-controller. As promising as the Innovatek Fan-o-Matic Pro looks, it IS an extra hardware layer, and then there's the *#%%&* price.
Between a rock and a hard place there. But it is not a serious concern. I just need to settle for more air-turbulence from the exhaust fans, leaving the CPU fan to spin up alone at the temperature threshold. I only want air to leak in one direction into the duct, so that's "Just what I gotta do, that's all . . . "
My own difficulty derives from the fact that (at the very least) ASUS is not implementing the fan-control features of anything but the CPU fan, despite the full potential of the WinBond super-IO controller. I want to balance and automatically vary the speeds of both my CPU fan and my exhaust fan(s), because they are connected with a ducting solution. That leaves me with the option of either connecting dissimilar fans to the CPU header when my currently-chosen CPU fan draws 0.80 Amp to begin with, or finding another software-driven, USB-connected automatic/programmable fan-controller. As promising as the Innovatek Fan-o-Matic Pro looks, it IS an extra hardware layer, and then there's the *#%%&* price.
Between a rock and a hard place there. But it is not a serious concern. I just need to settle for more air-turbulence from the exhaust fans, leaving the CPU fan to spin up alone at the temperature threshold. I only want air to leak in one direction into the duct, so that's "Just what I gotta do, that's all . . . "
After closer inspection, this is not an issue for my mobo, A8N-SLI. 350 mA to 2 A, 24 W per connector, up to 1 A to 3.48 A, 41.76 W max across five connectors.
BonzaiDuck
Lifer
- Jun 30, 2004
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Operandi wrote:
__________________
Let me clarify. This seems to be substantiated by the ASUS program "AI Booster" and the PDF documentation for AI Booster. It stands to reason that ASUS would implement the full capabilities of its mobo manufactures in its supporting software for a given motherboard. But neither the Booster software nor the documentation refer to anything other than CPU fan-control. The program may "read" and "display" the speeds for the remaining fan headers, but it will not control those speeds.
The Winbond super-I/O controller provides everything that the mobo manufacturer needs to implement full thermally-activated control of all fan speeds. But the manufacturer may choose to implement only some of those capabilities on their mobo. Apparently, on either the P4P800 and P4C800-E Deluxe, you can only CONTROL the fan speed for the CPU_FAN header. The remaining headers simply allow the fan to draw its top-end power.
__________________
Let me clarify. This seems to be substantiated by the ASUS program "AI Booster" and the PDF documentation for AI Booster. It stands to reason that ASUS would implement the full capabilities of its mobo manufactures in its supporting software for a given motherboard. But neither the Booster software nor the documentation refer to anything other than CPU fan-control. The program may "read" and "display" the speeds for the remaining fan headers, but it will not control those speeds.
The Winbond super-I/O controller provides everything that the mobo manufacturer needs to implement full thermally-activated control of all fan speeds. But the manufacturer may choose to implement only some of those capabilities on their mobo. Apparently, on either the P4P800 and P4C800-E Deluxe, you can only CONTROL the fan speed for the CPU_FAN header. The remaining headers simply allow the fan to draw its top-end power.
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